Lock
Type of lock - a device for fixing the main blade - used in a folding knife (see “Design”). Theoretically, such a device should provide additional protection by preventing unauthorized closing (and sometimes opening) of the knife; however, in practice, much depends on the type of particular lock: different types can differ markedly in reliability, and there are solutions that do not provide for rigid fixation of the blade at all.
Among the most popular modern locks are
liner lock,
frame lock,
back lock,
axis lock,
button lock and
tri-ad lock, however, in addition to them, there are other options, including
double auto,
compression lock,
viroblock and
slip-joint. Let's look at both in more detail:
— Liner lock. One of the simplest, inexpensive and at the same time very reliable locks. The locking element is an elastic flat plate (“liner”) hidden inside the handle; when opening the knife, this plate moves to the side and supports the back of the blade, on which a special recess is provided for the liner. To disengage the lock and close the knife, the plate must be moved with your finger in the other direction, to its ori
...ginal position.
- Frame lock. In fact, it is a modification of the liner lock described above, in which the role of the locking plate is played not by the liner installed inside the handle, but by part of the handle itself. Such a lock is considered more reliable, and on the whole it is deservedly so: the part of the handle that supports the blade is much thicker than the “liner” and is less likely to shift when the lock is opened. Also, the advantages of a frame lock include a rather interesting and stylish appearance: knives with such locks are mostly all-metal, without handle linings; and models with linings differ in appearance from knives with other types of locks.
— Back lock. A lock using a locking plate, which looks like a kind of spring-loaded “rocker arm” installed along the knife handle and capable of swinging around a transverse axis. When the knife is open, this plate, with its leading edge, rests against the hook on the back of the blade, preventing it from closing; and to close the knife, you need to press on the part of the “rocker arm” protruding from the handle, releasing the plate from the hook. The pressing force is usually quite large, which minimizes the likelihood of disabling the lock even with the tightest grip. In general, such locks turn out to be quite reliable, but it is very difficult to close a knife with a “backlock” with one hand, and in many models it is even impossible.
— Axis lock. Benchmade's invention: a lock controlled by a special movable pin in the front of the handle. When moved forward, the pin enters a groove on the back of the blade, fixing it; when moved back, the lock is released and the knife can be closed. The pin is often made spring-loaded, and the blade, unlike many simpler solutions, is fixed not only in the open position, but also in the closed position. Thanks to this, Axis Lock is considered one of the most reliable modern locks. On the other hand, such a mechanism is sensitive to contamination and requires some care (however, simple) for reliable operation.
- Button lock. Another lock based on the use of a pin. However, in this case, the pin does not move in the longitudinal groove, but is controlled by pressing a button: this press releases the lock, allowing you to open or close the blade (most often it is fixed in both positions - open and closed). Also note that many knives with a “push-button” lock have an automatic opening mechanism - a spring-loaded blade that opens into the working position without effort on the part of the user.
— Virobloc. A knife lock developed by Opinel and still a “calling card” of knives of this brand. The key element of the lock is a rotating ring with a longitudinal slot installed in the front of the handle, at the point where it connects with the blade. To open or close the knife (and it is fixed in both the closed and open positions), you need to turn the ring so that the slot is opposite the blade - then the blade can pass through the ring to the desired position. If the slot is not opposite the blade, the latter, when trying to open or close, rests against the ring and cannot budge.
- Slip-joint. A type of knife lock that does not provide rigid fixation of the blade. In the open position, the blade in such a knife is fixed by the so-called spacer - an elastic element that is to some extent similar to the back lock “rocker arm”, but does not engage in a rigid engagement with the blade (and also plays the role of a kind of closer for a not fully open blade). To close such a knife, it is enough to apply some force to the butt. “Slip joints” are used mainly in small Swiss knives (see “Type”), not designed for high loads.
— Compression lock. A modification of the Liner Lock described above, created by Spyderco and used in some models of this company. One of the key differences from the original is that the locking plate is located on the top side of the handle rather than on the bottom. Due to this, as well as some specific design solutions inside the mechanism itself, the compression lock turns out to be much more reliable than the original “liner”, however, such a lock is not cheap.
— Levitator lock. A proprietary modification of the Frame Lock (see above), developed by Benchmade. Like the original “frame lock”, it is used in knives without pads. A distinctive feature of “levitators” is a specific pattern of slots in the middle part of the handle - this pattern forms a spring plate. A pin is attached to this plate from the inside, which, entering the hole on the back of the blade, fixes it (usually in both the closed and open positions). The lock opens by pressing the characteristic part of the pattern, which acts as a button.
- Arc lock. A proprietary development of the SOG Specialty Knives company, used in its knives; from a technical point of view, it is a slightly modified version of the axis lock described above. The control element is also a pin; and the key difference from the usual “axis” is that the pin is connected to a special rocker arm and moves not in a straight line, but in an arc. This provides additional reliability, however, such disadvantages of the original as high cost and sensitivity to dirt are also characteristic of such a lock.
- Double auto. The Double auto system is not so much a type of lock as a type of opening mechanism found in frontal knives (see “Design”). This mechanism is controlled by a sliding switch that can move in two directions - unfolding (forward) and folding (backward). The whole system works in this way: when the switch moves forward or backward, one of the springs is charged, and when the extreme point is reached, the blade is released and moves in the corresponding direction under the action of the charged spring. In general, this is a very convenient and practical, and therefore very popular type of lock among front-facing cameras.
- Safe lock. The full name is Ram Safe Lock. Developed by Cold Steel, a specific variation on the back lock theme (see above): it also uses a rocker arm to rigidly fix the blade, only in this case the rocker arm does not swing, but moves back and forth. The blade is fixed in the open and closed position; To open the lock, you need to pull the rocker by the back part protruding from the handle. This design is highly reliable and resistant to loads; Its main disadvantage is the inability to unfold and fold the knife with one hand.
— Cogwheel lock. “Gear lock”, also known as a ratchet lock. The rear part of the blade has the shape of a gear in such knives, and the locking occurs due to a plate with a cutout for one of the gear teeth. To open the lock, you need to lift the plate; For this purpose, a characteristic ring may be provided in the design. An interesting (although not very useful in practice) feature of ratchet locks is the ability to fix the blade not only in open and closed, but also in several intermediate positions. At the same time, the reliability of such devices is relatively low, so they are rarely used - in particular, in models that copy certain types of traditional knives (such as the Spanish Navaja).
- Slide lock. A relatively rare type of lock, found in certain models of Swiss knives - usually small, but advanced and multifunctional, where the additional mechanism does not particularly affect the dimensions. This lock is controlled by a slider on the side of the handle: the blade is fixed in the open position, and to fold it you need to pull the slider back, thus disabling the lock. The slider is spring-loaded, which does not allow it to “slide” back on its own (for example, under its own weight); In addition, the spring also plays the role of a closer for the blade that is not fully open. The reliability of “slide locks” is not particularly high, but this is not required given the specifics of the application.
— Tri-ad lock. An invention of the Cold Steel company, which is a variation on the Back Lock mechanism. It also uses a locking plate in the form of a characteristic spring-loaded “rocker arm”, but it is secured in the center by a floating pin (oval, not round). Next to the front end of the “rocker arm” there is another axial pin - together, these modifications have significantly improved the reliability of the locking mechanism. Thanks to such modifications, the blades of knives with Tri-ad lock are devoid of any backlash.Blade profile
Profile of the main blade used in a knife.
The profile describes the overall shape of the blade; Its purpose and the features of using the knife depend on this. Among the most popular profiles nowadays are
drop-point,
clip-point,
normal blade (classic),
bowie,
tanto ; however, there are many other varieties such as
dagger,
wharncliffe, etc. It is worth noting that the difference between some options is quite arbitrary; the same actual shape from different manufacturers (and even from different sellers) may formally refer to different types of profile. So here we will look at the classic, most characteristic features of the different options. They are:
— Normal blade (classic). The traditional profile of the blade, in our area known, in particular, from Finnish knives (finks). The butt of the “classic” is strictly straight (this is the main difference from the drop point), while the blade has a straight shape in the back and middle parts, and in the front it is rounded upward and forms a pronounced tip. This shape makes the blade easy to manufacture and at the same time universal; it works equally well for cutting and piercing, allows the knife to be used for planing, etc.
— Drop-point. The profile is in man
...y ways similar to the normal one described above and differs primarily in the shape of the butt - it is not straight, but somewhat bent downward in an arc closer to the tip. It is also universal, while the proximity of the tip to the load axis contributes to higher efficiency when working on a puncture (although in general such blades are not considered as a serious piercing tool). Thanks to this, as well as ease of production, low cost and reliability, drop points are extremely popular in modern knives.
— Clip-point. Another universal profile, similar in shape to a drop-point, but differing in one characteristic detail: the front part of the butt, going down to the tip, is made not in the form of an arc, but in the form of a straight bevel at a relatively small angle. This further increases the effectiveness of the piercing effect; clip points are considered more "aggressive" than drops, and better suited for use as a weapon. However, such knives are still primarily tools and also perform well in this role, and in a fairly wide variety of tasks.
— Bowie. A profile originally created for combat and hunting knives. The shape of the blade itself is similar to the options described above - it is straight in the back and middle parts and smoothly curved to the tip in the front. But in terms of the shape of the butt, the “bowie” is a kind of opposite of the “drop point”: the front part of the butt is made not convex, but concave, as a result, the tip turns out to be “snub-nosed”, slightly raised up. Many value such blades primarily for their characteristic external style, but they also have very practical advantages: a center of gravity shifted back (which is especially noticeable on large, heavy knives) and high efficiency both when cutting and when piercing, which is enhanced in some models the presence of sharpening on the concave part of the butt.
- Tanto. Originally, a tanto is a traditional Japanese dagger; however, modern knives most often use not the classic shape, but the so-called “American tanto”, with a characteristic angular blade shape. Actually, the blade in such knives is straight or slightly curved (convex) along almost the entire length, but closer to the tip it sharply bends upward, forming a clearly defined angle (Japanese tantos do not have such a break and the blade bends smoothly). The American tanto is distinguished not only by its stylish, “aggressive” appearance, but also by its excellent stability when piercing (as well as efficiency when cutting), which is what determined its wide popularity.
— Spay-point. A type of profile similar in shape to the clip-point described above, but having a larger bevel angle. As a result, the angle of the tip where the butt and blade meet is more blunt, which reduces the effectiveness of deep piercing blows, but makes the blade more durable and resistant to various loads. The latter can be very useful for various chores; in particular, spay-point is quite popular among skinners - hunting knives used for skinning prey.
— Spear-point. A type of profile inspired by the tip of a spear. A full-fledged spear point has symmetrical outlines, sharpening on both sides and is used mainly in combat and hunting knives; the shape of such a blade is designed primarily for efficiency in stabbing strikes. However, there is also a simplified, more “peaceful” version of this profile: its shape is similar to the drop point (see above), but on the front of the butt, in front of the tip, there is an additional descent that forms a false blade or even a full-fledged additional blade. Such “spear points” have mainly economic purposes.
— Dagger. The profile shape derived from daggers: a double-edged blade, usually long and narrow, strictly symmetrical in shape, with a clearly defined tip. In many ways similar to a spear point, however, it is designed not only for piercing, but also for cutting; some models may even have different sharpening on different sides of the blade (smooth on one side and serrated on the other).
- Сhisel. This name translates as “chisel”, and it quite clearly describes this type of profile. Such blades have a rectangular or similar shape, there is practically no point in them, and on the front side of the blade there is an additional cutting edge located perpendicular to the main blade. In general, chisel is a rather highly specialized and therefore poorly widespread type of profile: it is convenient for some specific work, but in terms of overall functionality and practicality it is inferior to many of the options described above.
— Clearer blade. A profile similar in shape to the blade of a kitchen hatchet: wide, massive (however, holes are often made in the blade to reduce weight), with a straight or slightly rounded blade shape and often without a pronounced tip - the front part of the blade in such cases looks perpendicular or almost perpendicular cut. Many of these models are similar to the chisel blades described above, but the leading edge in the “jibs” is not sharpened. There are, however, other variants of the shape - for example, with a blade clearly rounded upward and a bevel of the butt, reminiscent of a shortened and thickened version of a clip-point or bowie (see above). However, in any case, cleaver-type blades are designed mainly for cutting and sometimes chopping, and are poorly suited for thrusting or not at all.
- Sheepsfoot (“sheep’s hoof/sheep’s leg”). A profile that is a kind of opposite to the “classic” described above: the blade in such blades is made straight or almost straight, and the butt in the front part is rounded down towards the blade. As a result, the tip turns out to be as non-aggressive as possible, practically incapable of piercing. Due to this, the “sheep’s leg”, among other things, is considered an ideal option for a rescue tool: with such a knife you can, for example, cut a seat belt that fits tightly to the body without fear of injuring a person.
— Wharncliffe. A profile reminiscent of the sheepsfoot described above; sometimes these two options are even combined into one type. However, there is still a difference: in the Wharncliffe, the butt in the front part descends to the tip along a gentler arc than the sheepsfoot, and this arc begins noticeably closer to the handle. The advantages of this profile are considered to be high cutting accuracy (due to the straight blade along the entire length), as well as good suitability for planing and scraping (for the same reason). In addition, the tip also turns out to be quite functional; it can, for example, accurately cut out a shallow contour of a complex shape. However, in general, this profile is not as versatile as the same “classic” or “drop point”; It initially gained popularity in “gentleman’s knives” - small pocket folding models of the EDC category. It is also worth noting that there are several other variants of the “wharncliffe” on the market - with a slightly curved upward rather than straight blade.
- Skinner A profile found exclusively in hunting knives and having a rather narrow specialization - “skinner”, as the name hints, is intended for skinning hunting trophies. Accordingly, the shape of the knife is optimized for maximum convenience during such work. The blade is made quite wide, often also quite short. In shape it is somewhat reminiscent of a drop point (see above), however, “skinners” have an extension closer to the tip, and the tip itself may not be provided at all - knives of this type are not designed for piercing action. Because of these features, “skinners” are practically unsuitable for use for any purpose other than their primary purpose; It makes sense to buy such a knife in addition to a universal hunting knife (or an “arsenal” of several knives).
- Gut-hook. Modification of the drop-point profile (see above), found in hunting knives. On the butt of such a blade, at the very tip, a special hook is made with a sharpened inner edge; This type of hook is convenient for skinning and butchering prey. At the same time, the knife turns out to be almost as universal as the original drop-point - thanks to the similar outline of the blade; The only thing is that the gut-hook is not well suited for strong stabbing blows, since the presence of the hook somewhat reduces the strength of the blade. We also note that almost all such knives are made non-folding - this design for “gut-hooks” is considered optimal, taking into account the profile features.
— Persian-point. A profile somewhat similar to the bowie described above and differing primarily in the shape and size of the concave part of the tip: it occupies most of the butt, and sometimes the entire butt is made concave. We also note that the degree of curvature of the butt can be different - from an almost straight shape, slightly different from the “classic”, to a pronounced arc of a bizarre shape, with a variable bending radius. Persian-point is one of the “historical” profiles used since ancient times; it allows you to use the knife with equal efficiency both as a weapon (including for stabbing) and as a tool for various household tasks. However, the features of application greatly depend on the specific shape of the blade.
—Hawkbill A downward curved sickle-shaped blade, reminiscent in shape of the beak of a bird of prey. The tip of such a blade is obtained noticeably below the center line, and sharpening is carried out along the inner, concave side of the blade. Classic representatives of “hawkbills” are karambits - knives originally created for a rather specific application; See "Type" for details.
- Recurved blade. A profile suggesting an S-shaped blade - slightly tapering from the base to the first third, noticeably widening towards the second third and with a clearly defined tip; the butt shape is usually similar to the drop-point profile (see above). Many consider the stylish and aggressive appearance to be one of the main advantages of this profile. As for functionality, the recurved blade is intended mainly for chopping, rough cutting and ripping; For piercing effects, as well as precise cutting, such knives are poorly suitable.
- Latin. Traditional, the most common type of profile among machetes; originally appeared in Latin America, hence the name. The latin blade has some expansion closer to the tip, most of the blade, starting from the handle, is flat, but closer to the end of the blade the blade rises in a steep arc towards the tip. The butt is straight or slightly concave; in some models it may be equipped with a serrator or even a full-fledged saw. Like all machetes, “Latin” blades are intended primarily for chopping, which is facilitated, in particular, by the blade’s center of gravity shifted to the tip; For more information on the use of such tools, see “Type”.
- Golock. Blade profile originating from Malaysia; found exclusively in machetes. Initially, the “golok” is a heavier, thicker and at the same time shorter profile than the traditional “Latin”; it provides for a noticeable expansion towards the end and a cutting edge rising steeply towards the tip, which gives the blade a distinct teardrop shape. However, nowadays, under the designation golock, blades are produced that are very far from the original configuration and resemble drop-point, or even sheepsfoot (see above).
— Parang. Another type of machete comes from Malaysia: a large and heavy blade of a curved shape, with a convex (curved upwards to the tip) cutting edge and a noticeable expansion from the handle to the end (more pronounced than in classic Latin-type machetes). The tip itself is most often located at the line of the blade, but it can also be located higher, in the area of the butt line. We also note that the “parang” profile also includes requirements for the handle: it must be curved downwards and have a thickening at the end for a secure hold in the hand. Thus, the overall shape of such a machete is S-shaped. Due to their shape and heavy weight, parangs allow you to chop effectively with a small swing.
— Kukri. Profile used in knives of the same name; In our catalog, such knives are classified as machetes, but initially “kukri” is a separate type of heavy knife, whose homeland is Nepal. This profile is difficult to confuse with something else: the long (several tens of centimeters) blade is curved downwards, noticeably widened near the tip and sharpened along the inner, concave side. This shape, combined with a forward center of gravity, makes the kukri extremely effective for chopping. Such knives are also used as combat knives, but in general they are very versatile tools, suitable for peaceful use in tourism, agriculture, etc.
- Bolo. The blade profile of the machete is also known as “Filipino” - based on its place of origin. The peculiarity of such a blade is that starting from the second third (when viewed from the handle), it expands in both directions - both towards the blade and towards the butt - and then converges to the tip, located almost on the center line of the knife (usually slightly above or a little lower). The blade itself can be either convex or S-shaped, like a recurved blade (see above). Initially, the “bolo” was an agricultural tool; its original purpose was to cut down bushes and small trees.Main blade type
The shape of the cutting edge of the main blade of the knife.
-
Smooth. Traditional cutting edge without serrations. This option is considered the most versatile, with the proper degree of sharpness, smooth blades are suitable for almost any work that uses knives. They lose their properties faster as they become blunt than serrated ones; on the other hand, the sharpening procedure is very simple, does not require specific equipment or skills, and is available to almost any knife owner.
-
Serrated. Blade with characteristic teeth on the cutting edge. In addition to the formidable appearance, such knives have quite practical advantages. One of them is the ease of cutting - at this point, the serrated edge is much superior to the smooth one. In addition, it retains its cutting properties, even when thoroughly dulled, due to the way the teeth themselves interact with the material being cut. Also, these knives do a good work with some specific tasks - for example, cutting dense fibrous materials like ropes or cutting soft foods with a dense crust. At the same time, the teeth cut less smoothly and cleanly than a smooth blade (although they do not create sawdust, unlike a saw), and it is much more difficult to sharpen them again after dulling. Therefore, this type of sharpening in its pure form is rarely used for the main blade - more often it can be found in specialized tools like
sling cutters(see "Functions and Capabilities").
- Combined. Blades that combine both types of cutting edge described above. As a rule, smooth sharpening in such models is used in the front, closer to the tip, and serrated sharpening is closer to the handle. This provides a certain versatility: depending on the specifics of a particular task, the owner can choose the optimal type of cutting edge. On the other hand, working with such a knife may require some skill; and the main drawback of serrated blades - the difficulty in sharpening - has not disappeared here either (although the smooth part is sharpened without problems).
Steel grade
The grade of steel from which the main blade of the knife is made. Knowing this name, you can find detailed data on the steel used and evaluate how high quality the knife is, whether it is suitable for the intended application and whether it is worth the money. Here are some of the most popular brands today:
— 440A, 440B, 440C. Category "above average". Relatively inexpensive varieties with excellent value for money. The carbon content is 0.75%, 0.9% and 1.2%, respectively; 440C steel is considered the most advanced, however, all varieties are resistant to corrosion, keep sharpening well and at the same time are quite easy to sharpen.
— AUS-8. The Japanese analogue of the "440th" line — more precisely, steel 440B (analogues 440 A and 440C are marked AUS-6 and AUS-10). It is distinguished by the presence of vanadium in the composition, which has a positive effect on wear resistance.
— 8Cr13MoV, 8Cr14MoV, 5Cr15MoV, etc. Chinese grades of steel with the addition of chromium, molybdenum and vanadium. The most popular and advanced option is deservedly considered "eight-chrome-thirteen". It is similar in properties to AUS-8, but has a higher carbon content; such steel is relatively inexpensive, but it has very good performance characteristics, due to which it is found both in relatively inexpensive knives and in premium models.
— 420. The material of the low-cost category, which, however, is distinguished by excellent corrosion resist...ance. Such steel wears out quickly, but it is also very easy to sharpen; it is well suited for low-cost knives designed for daily use.
— 420HC. A slightly more advanced version of the 420 steel described above, having a higher carbon content. As a result, the 420HC is noticeably harder and holds an edge longer; in terms of resistance to corrosion, it is practically not inferior to the original, but costs only slightly more. It is also considered an excellent option for mass-produced low-cost knives.
— D2. Category "significantly above average". A distinctive feature of this steel is its high chromium content, due to which, in terms of corrosion resistance, it approaches full-fledged “stainless steels” (although it still falls short of them). In addition, D2 is noticeably harder than most materials of a similar price category, due to which it is quite difficult to sharpen, but retains its working properties for a long time.
— CPM. A family of steels from Crucible that includes premium and super premium grades. Manufactured using the Crucible Particle Metallurgy proprietary technology, which, according to the manufacturer, provides higher quality than traditional production methods; however, such materials cost accordingly. The specific characteristics of different grades, of course, vary somewhat, but they are all characterized by good hardness and corrosion resistance. However it is worth considering that certain types of CPM (especially the most expensive ones) can be very difficult to sharpen; on the other hand, such sharpening is maintained noticeably longer than in cheaper materials.
— 65X13. Perhaps the most popular brand of Russian-made steel. It has a high chromium content, which contributes to corrosion resistance, while it is quite easy to sharpen, but does not differ in hardness. It is inexpensive and is used mainly in the mass production of inexpensive knives.
Blade length
The total length of the knife blade. This characteristic is one of the most important, with several practical points associated with it.
Firstly, the length of the blade is directly determined by the purpose of the product, and even within the same type (see above) there may be different options. For example, hunting knives for skinning (skinners) are usually quite short, up to 10 cm - in contrast to general-purpose options. Therefore, it is worth choosing a model according to this parameter, taking into account the work for which you plan to use the knife.
Secondly, the dimensions of the blade determine the overall dimensions of the knife itself. This is especially important for outdoor models (see "Type"): although the knife is usually worn folded, it is customary to indicate its dimensions in the specifications for the unfolded position. And by the length of the blade, you can quite clearly estimate the length of the knife when folded: usually it is 1.5 - 1.7 times longer than that of the blade itself, and in any case, the knife cannot be shorter than its own blade.
Thirdly, the length of the blade can be (and in many CIS countries is) one of the criteria for determining whether a knife belongs to a cold weapon. Usually, regulatory documents indicate a certain minimum length value: shorter blades do not fall into the category of edged weapons, regardless of their design, and for longer blades, specific evaluation criteria come into force...(hardness of the material, shape of the point, blade thickness, etc.).
At the same time, it should be borne in mind that the length of the blade can be measured in different ways: from the point to the beginning of the handle, from the point to the peg used in opening, etc. In practical application, this moment does not play a decisive role, however, it can create legal problems: for example, state examination methods may not take into account the peg. So, if you have doubts about this, it is best to purchase a knife that has an official certificate that this model is not a melee weapon.
Blade thickness
The thickness of the knife blade at its thickest point (usually at the butt). According to this parameter, one can to some extent evaluate the strength of the blade for transverse loads: a large thickness gives an appropriate margin of safety. At the same time, one should not forget that the “endurance” of a knife as a whole depends on many other features of its design, and only blades made of materials similar in properties can be compared in thickness. But what this indicator directly affects is the weight of the product.
Also, legal issues can be associated with the thickness of the blade, which determine whether a particular knife belongs to a cold weapon and the corresponding rules for buying, wearing and storing. The relevant rules may state, for example, that blades with a thickness of more than a certain value cannot be classified as melee weapons, regardless of other features.
Weight
The total weight of the knife. It is worth evaluating this indicator depending on the type (see above) and purpose: for example, for a compact hiking model,
light weight is usually a virtue, among hunting and fishing it all depends on specialization, and a machete, by definition, must be
weighty — otherwise, cut with such a blade it will just be uncomfortable.