Comparison Casio A-700WEM-7A vs Casio B640WD-1A

The accuracy of the rate is usually determined by the largest error — the deviation from the reference time, which can occur in a month when the watch is constantly running in normal mode. Accordingly, the smaller the number in this paragraph, the more accurate the clock. In addition, the accuracy of the movement is a kind of status indicator: if the error exceeds the values stated in the characteristics, this may indicate a malfunction in the mechanism.

If the accuracy indicators are the same both in advance and in lag, one number is indicated in the characteristics — for example, 30 sec / month (i.e. +/-30 sec / month); however, many mechanisms have unequal deviations, for example -15/+25 sec/month. Also note that this parameter is relevant only for quartz watches (see “Movement type”): in mechanical models, the accuracy of the rate is noticeably lower, it is measured in seconds not per month, but per day.

— Alarm clock. A classic alarm clock is an audible signal that works at a time specified by the user. It can be used not only for getting up, but also as a reminder of a particular event. Note that in mechanical models (see "Type of mechanism") this function is almost never found.

— Stopwatch. A traditional stopwatch is a function that allows you to measure time intervals with an accuracy of seconds, or even fractions of a second. In modern watches, you can find two types of stopwatches. The first is the solutions used in models with displays (in other words, in watches with electronic and combined dials). In such devices, the countdown of seconds is displayed on the screen and is accurate to a tenth or even a hundredth of a second; Also, such stopwatches can have various additional functions: counting intermediate results for control points or laps, saving the results of the last measurement, etc.
The second type of stopwatch found in the arrow dials is the arrow on the main axis, which can be started and stopped at the request of the user. This is a rather rare option — for the reason that most often such an arrow is used in combination with additional scales and is no longer a stopwatch, but a chronograph (see below). And in watches where there are no chronograph scales, a rather unusual format for the operation of such a hand can be provided: in normal mode, it works like a standard second,...and when the watch is switched to stopwatch mode, it moves to zero and stops before the countdown begins.

— Timer. Countdown function; at the end of the countdown, an audible signal sounds. This function is convenient in cases where you need to measure a strictly defined period of time — for example, when cooking in the kitchen: “starting” the timer for the desired period is much more convenient than counting the hour you need to set the alarm.

— Day of the week. Ability to display the day of the week on the watch face. It is found both in watches with displays and in purely analogue models — they use a mechanical indicator for 7 days.

— Day of the month. The ability to display the current day of the month on the clock face. It can be either a number on the display or a mechanical indicator in the form of a window with a number. Note that in the latter case, regular adjustment of the calendar is required: the mechanical pointer is designed for 31 days, and if there are less than 31 days in the past month, the displayed date will have to be “scrolled” forward.

— Month of the year. Ability to display the current month on the watch face. Usually, it is combined with an indicator of the day of the month, and often also the day of the week; thus, the presence of this pointer means that the watch is equipped with a full-fledged calendar. Most often, the display is responsible for this function, but there are also purely arrow models with similar equipment. The month indicator of the year is often synchronized with the day indicator — so that the watch itself determines how many days are in the current month and after which day you need to switch to the first number.

— World time. The ability to use the clock to determine the time in other time zones than the current one. The specific way in which such a function is implemented may vary. Thus, the most popular option in hand models (see "Dial type") is the presence of an additional dial, on which the time of the time zone of interest is set. This format is convenient in cases where you constantly have to deal with a certain region — for example, to communicate with relatives or business partners from a particular country. Another option is the indexes on the rotating bezel (see below), corresponding to the main time zones of the world; to determine the world time, you need to turn the bezel so that the current time zone is opposite the hour hand — then the remaining marks will be opposite those divisions of the dial that correspond to the time in these time zones. This format is convenient for frequent change of time zones — in particular, it is found in watches for sailors. And models with digital dials usually provide switching the screen between the current and additional time zone (zones).


— 12/24 hour time format. This feature is indicated only for watches with pointer dials (and certain pointer-electronic models, see "Dial type"). It means that in addition to the main 12-hour scale, the watch also has a small dial with 24-hour markings. It allows you to determine what time the main scale shows — before or after noon: for example, at 6 pm the main dial will indicate 6 o'clock, the additional one — at 18 o'clock. — for example, in the conditions of a polar day / night, or during a long stay underground.
As for watches with electronic dials, even the 12-hour format is supplemented with the note "AM" or "PM" ("am" and "pm" respectively); for example, 20:00 would be 8:00 PM. So in such models there is simply no need to provide special functions for determining the time of day.

— The phases of the moon. The presence of an indicator in the watch that displays the current phase of the moon. Many processes on Earth depend on the phases of the Moon (in particular, the general physical and mental state of people), a number of signs are associated with them — not always 100% reliable, but not having an unequivocal refutation. A separate category of watches with a lunar calendar — "fishing" and "seafaring" models; the latter may even provide a separate tide calendar.

— Chronograph. Analogue of a stopwatch used in watches with pointer dials (see "Dial type"). Such watches have several additional small scales, each of which performs its own function. For example, one of these scales can be responsible for counting minutes (up to half an hour), the second — for counting hours (up to 12 hours), the third is the usual second hand, and the hand for counting seconds is located on the central axis and remains stationary until the chronograph is turned on.

— Tachymeter. A device for measuring the speed of movement by the time during which the measured section was passed. The tachymeter most often has the form of an additional scale for a stopwatch, and to measure the speed, you need to measure the time it takes to pass the control section with a stopwatch and see what number on the tachymeter scale the stopped arrow points to. In this case, the measurement time should not exceed a minute (otherwise the arrow will go to the second circle, and the readings will be unreliable), and additional calculations may be required to determine the final result. However, anyway, it is much more convenient to use tachymeter data to determine speed than stopwatch readings.

— Slide rule. Built-in mechanical calculator for some simple mathematical calculations, primarily multiplication and division. Such a device can be useful, in particular, for calculating travel time, fuel consumption, transferring money from one currency to another, etc. In hours, a slide rule usually consists of two rings with divisions (hence the second name for this function is a calculator ring ). One of these rings is motionless, and the second rotates freely; combining the marks on both scales according to certain rules, the user gets the desired result. Note that the slide rule is not as accurate as an electronic calculator and is more difficult to handle; on the other hand, with a minimum skill, elementary calculations on it can be carried out much faster than on the same calculator.

— Compass. A traditional compass is a device for determining cardinal directions. The accuracy of built-in compasses is usually not high, but they can be very useful for simple tasks or as a last resort when other navigational devices are not available.

— Altimeter (altimeter). A device for measuring the current height of the terrain. Often combined with a barometer (see below), in such cases the difference in pressure between the reference level and the current location is used to measure altitude. Technically, in this way it is possible to measure the height both above sea level and relative to a certain place taken as a standard; actual altimeter capabilities vary by watch model. Watches with this function are designed primarily for climbers and mountain hikers.

— Thermometer. Thermometers in watches are usually designed to measure the temperature of the surrounding air. This feature is found mainly in advanced sports models. It can be useful both for a general assessment of the environment, and for specific tasks such as weather forecasting, calculating the current altitude, etc.

— Barometer. A device for measuring atmospheric pressure. Data from the barometer allows you to assess the weather conditions and their favorableness for a certain type of activity — in particular, fishing. In addition, they can be used to predict changes in the weather: for example, a sharp drop in pressure is often a sign of an approaching storm. Also, the operation of the altimeter (see above) is often based precisely on the readings of the barometer.

— Bluetooth. The Bluetooth wireless interface is designed to communicate between various electronic devices over relatively short distances — up to 10 m. In wristwatches, it is mainly used to communicate with a smartphone or other gadget. The functionality of such a connection may be different, but anyway, it is much narrower than in smartwatches. The most popular features include displaying notifications from Facebook and/or Twitter on the watch, using the watch as a remote control for music or video, as well as setting the world time (determining the time zone from data from an external device).

— GPS module. Built-in satellite navigation module that allows you to determine the current geographic coordinates of the device. How this data is used may vary depending on the watch model. So, in some models, data on time zones in different countries are sewn in, and based on the current coordinates, the device can determine the exact local time. Another option is to record the routes (tracks) traveled. Some watches use GPS data for altimeter operation (see related paragraph). Models with Bluetooth may provide the ability to work as an external sensor for a smartphone or other gadget (it is believed that the hand position of the sensor improves accuracy). But it is difficult to provide full-fledged navigation in traditional watches; wearable gadgets with such functionality usually refer to either smartwatches or specialized navigators.

— Synchronization by radio channel. This function allows the watch to receive special time radio signals. These signals are transmitted over a special dedicated channel several times a day, and the exact time data is received from atomic chronometers used in scientific institutes. The error of such chronometers is 1 second for several thousand or even millions of years; accordingly, the accuracy of the clock synchronized with them is almost absolute. At the same time, note that precise time radio signals are not available in all countries of the world — so before buying such a watch, it's ok to check whether they will work in your region.

— Chronometer. In this case, the designation "chronometer" is used for high-precision models that are certified by the Swiss Chronometer Certification Centre (COSC). To obtain such a certificate, a watch must pass a fairly rigorous test, checking not only for overall accuracy, but also for the ability to maintain it with changes in case position and ambient temperature. At the same time, it should be noted that in fact "chronometric" accuracy is required extremely rarely, and it affects the cost of watches quite noticeably. So compliance with the COSC requirements is not so much a practically significant moment as an indicator of the high class of watches and the status of their owner.

— Pedometer. Built-in counter of the number of steps taken by the user. This feature is found predominantly on sport touring models equipped with Bluetooth (see above) and digital or combination watch faces (see "Dial Type"). To count steps, usually, data from the built-in accelerometer is used, and the measurement results can at least be transmitted to a smartphone or other gadget, and in some models they can also be displayed on their own screen. However, it's ok to clarify the specific features of the functionality of a watch with a pedometer separately.

— Phone search. Feature exclusive to Bluetooth models (see above). In accordance with the name, it facilitates the search for a “lost” phone located in close proximity (for example, forgotten in one of the home rooms): just give a command from the clock and the device will “respond” with a sound signal. Usually, to use this function, you need to install a special application (other additional functions are usually implemented through it, if available — for example, a pedometer).

The shape of the watch case; most often the dial has the same shape, but there are exceptions (for example, a rectangular display in a round case).

This parameter practically does not affect the functionality, so the choice in this case is related solely to how convenient and pleasant-looking one or another option is for you. Also, shape data can be useful if the watch is chosen as a fashion accessory that plays a well-defined role in the image being created. As for specific options, round cases are the most common nowadays — they are easy to manufacture, look neat and fit almost any style of watch. Rectangular watches are also quite popular, they can also belong to different styles; however, such cases are more bulky than round cases, and therefore are used less frequently. The square shape is actually a variation of the rectangular shape. Oval is considered to be suitable primarily for women's watches, although there are also single men's models with such cases. There are other types of cases — polygonal, barrel-shaped, as well as products in non-standard design.

The main colour of the watch case.

Modern watches are quite diverse in colour options. The most widespread models are in shades of " stainless steel ", golden and black ; however, in addition to this, on the market you can find, in particular, white, yellow, green, brown, red, orange, pink, silver, grey, blue and purple cases.

In general, the colour of the case is a fairly obvious parameter; Let's note only some of the nuances associated with marking:

— Multi-coloured models include models in which there is no clearly defined primary colour. If there is such a colour, it is indicated in the characteristics. And for two-tone cases, an additional colour can be specified, for example, "stainless steel with gold " or "black with blue "

— Silver, among other things, are plastic cases without additional coloring.

— "Stainless steel" in this case is a colour, not a material; other metals (e.g. alumin...ium and titanium) that are not complemented by PVD coating (see “Case Coating”) may have this shade. And the cases of gold watches, in turn, are not necessarily made of gold — red and white gold are also used in jewelry.

— Camouflage coloring is indicated separately — such watches are designated as "military", and here, again, the main shade of the coloring is given. However, not every military model has camouflage on the body; see below for details.

The material from which the bracelet/watch strap is made. Note that the division into bracelets and straps is rather arbitrary, the basis for it is precisely the material. In modern watches, there may be such options:

— Nylon strap. Nylon is a synthetic material that has a characteristic structure in the form of interwoven threads in watch straps. In most cases, these threads are quite large, due to which the nylon straps are similar in appearance and texture to the ties of tourist backpacks; this option is typical for sports watches. However, there is another variety — finely woven nylon, which is used mainly in women's watches (see "Gender"). Of the practical properties of this material, it is worth noting, first of all, unpretentiousness and resistance to water, including salty; in addition, it can be given almost any colour, and the combination of multi-coloured fibers allows you to create original and bright straps.

— Rubber strap. In this case, rubbers mean elastic materials that, in terms of properties, are a cross between plastic and rubber. Rubber is denser, harder and stronger than rubber, while noticeably softer and more flexible than plastic, which allows it to be used for watch straps. Of the advantages of this option, it is worth noting, first of all, high wear resistance and moisture resistance, which, combined with the appearance features, makes these straps a good option f...or watches in a sporty design. But among the classic models, rubber is usually used in inexpensive watches and has rather modest characteristics.

— Leather strap. Genuine leather straps are typical for quite expensive watches: this material is expensive, while it has a solid and rich appearance. In addition, it is notable for its high strength, moisture resistance and durability. Of the shortcomings of the skin, in addition to the price, it is worth noting a certain tendency to scratches, as well as increased care requirements — otherwise the product may lose its “presentation”.

— Leatherette strap. As the name suggests, leatherettes were created as an alternative to real leather. Their main advantage is a relatively low price: being practically indistinguishable from a leather bracelet, such a bracelet will cost much less. On the other hand, this material is less durable, wears out rather quickly and is generally not so reliable. Note that today different types of leather substitutes are used, and the quality of this material usually directly depends on its price.

— Steel bracelet. The watch bracelet consists of links connected to each other; in this case they are made of stainless steel. This material is strong, durable, practically not subject to corrosion, moreover, it has a solid appearance and is quite pleasant to the touch; at the same time, the cost of steel allows it to be used even in inexpensive watches. Such bracelets are quite “heavy”, however, some owners consider this moment to be a virtue, because. it gives a feeling of solidity and reliability. And of any significant shortcomings of steel, one can only note high thermal conductivity — the bracelet will noticeably “cool” the hand if the watch has lain in the cold for some time (though not for long — just a few minutes).

— Milanese bracelet. Milanese are called metal bracelets made of links of very fine weaving (about 1 mm in size, or even less). The material of such a bracelet may be different; most often it is steel, but more expensive metals are also found. Anyway, such a bracelet has an original appearance, and also provides good air access, allowing the skin to breathe. Among the shortcomings of Milan, it can be noted that the links can “bite” the hair on the arm, creating discomfort. Thus, and also to keep the cost down, some watches do not use Milanese weave on the entire bracelet, but only on part of it (usually it is about half of the entire bracelet).

— Titanium bracelet. Bracelets made of titanium alloy are much stronger than steel, with less weight. They also conduct heat less well, making them better suited for cold weather. At the same time, titanium is characterized by almost all the same advantages: high strength and reliability, solid appearance, resistance to corrosion. Its main disadvantage is the high price, due to which this type of bracelet is found mainly in premium watches.

— Gold bracelet. Jewelery gold bracelets are mainly used with cases made of the same material (see the relevant paragraph). A watch with a gold bracelet is not so much a device for measuring time as a status accessory, or even a piece of jewelry; the latter is especially characteristic of female models.

— Silver bracelet. Silver bracelets are found exclusively in watches with cases made of the same material. Like the gold described above, this material is used not so much for practical as for fashion reasons — in order to give the watch a rich appearance and emphasize the status of its owner. At the same time, for a number of reasons, silver bracelets are extremely rare.

— Ceramic bracelet. A premium material found predominantly in women's watches (although there are also men's models with ceramic bracelets). Ceramic not only looks good, but also retains its original appearance for a long time — thanks to its excellent resistance to scratches, dirt and stains. In addition, this material has a relatively small weight; and the high cost in this case is more of a virtue — it emphasizes the high level of watches. Among the shortcomings of ceramic bracelets, some fragility can be noted — a strong blow can split the links.

— Plastic bracelet. This category includes both the actual bracelets, woven from individual links, and straps made of flexible plastic. The second variety is similar to rubber straps, see the relevant paragraph for more details. As for the bracelets, they are usually combined with cases made of similar materials (plastic or carbon), and can be used in different categories of watches — both relatively inexpensive and quite advanced. The quality of plastic in this case, usually, is directly related to the price category of the device.

— Tungsten bracelet. Bracelets made of tungsten alloy are highly durable and reliable; these properties are further emphasized by the fact that tungsten has a very high melting point. And yes, it does look good. At the same time, it does not have key advantages over other premium alloys (titanium, see above) and is noticeably more expensive due to the complexity of production. As a result, such bracelets are extremely rare, mainly in combination with cases made of the same material (see "Case Material").

— Aluminium bracelet. Quite a rare option, found in single watch models. Bracelets made of aluminium are lighter than steel, they are not inferior to them in terms of strength and reliability, however, they are more expensive.

A mechanism that allows you to quickly change the length of the bracelet without disassembling it or using additional devices. Usually performed in the form of a miniature screw, by turning which, you can adjust the length; the range of such adjustment is most often of the order of 10 – 15 mm.

Such a mechanism is relevant primarily for watches with a clip-on clasp (see the relevant paragraph). With traditional adjustment, the clasp has to be disassembled, which requires both tools and certain skills. The quick extension system, in turn, is extremely easy to use and is available even in a complete "separation from civilization" — for example, in nature.

As the name suggests, this parameter determines the degree of resistance of the watch to moisture. It is traditionally stated as the maximum depth under water at which the watch is able to remain watertight; however, it must be borne in mind that this number is very arbitrary. The fact is that when calculating the maximum immersion depth, only the static pressure of water is taken into account, that is, the pressure at complete immobility; at the same time, any movement creates dynamic pressure, which significantly increases the load on the body. In practice, this means that a mark of, for example, 50 m does not mean that you can dive to a depth of 50 m with a watch.

Modern water protection markings correspond to the following practical possibilities:

— 30 m(same as “Water Resistant” without any numbers). Entry level, drops of water are allowed, but not strong splashes. For example, such a watch can be left on in the rain or when washing, but when showering or washing a car, it should be left in a safe place. Of course, there is no talk of immersion in water.

- 50 m. Minimum water resistance, allowing the watch to be immersed in water. These watches can usually be used for swimming, and in some cases even jumping into the water (but not from towers), but they are not suitable for more serious tasks like surfing, snorkeling or scuba diving. As a rule, buttons are not allowed to be...used underwater.

- 100 m. This degree of water protection allows not only swimming, but also diving to shallow depths, however, it is still considered insufficient for surfing, jumping from towers and scuba diving.

- 200 m. Watches with such water protection are classified as “divers”; models and can withstand scuba diving to depths of up to 20 m.

- 300 m or more. Professional diving models suitable for diving to significant depths.

Please note that the characteristics described are approximate. Specific indicators of water resistance and the possibility of using the watch with water should be clarified according to the official data of the manufacturer.

The nominal size of a watch case in diameter (for round cases) or width (for other options, see "Case Shape"). In the most miniature modern models, this size is 21 – 25 mm or even less, among the largest there are cases of 46 – 50 mm and even larger.

Larger watches are more convenient in the sense that the dial readings are better visible on them, and it is easier to provide various additional functions in the design. On the other hand, small watches look neater and create less discomfort directly when worn. In addition, female models (see "Gender") are traditionally made more miniature than male ones. So the choice for this indicator depends mainly on the intended specifics of the application: for example, large cases are best suited for outdoor activities and tourism, about 41 – 45 mm in size, for household wear (regardless of gender) — about 31 – 35 mm, and as an accessory to an evening dress, a small watch of 30 mm or less would be more appropriate.

Also note that the size of a compatible strap/bracelet is associated with this indicator — see "Strap Width" for details.

The thickness of the watch case. A fairly obvious parameter; we only note that nowadays it is customary to attribute watches with a thickness of less than 7 mm to ultra-thin models. This design has both aesthetic and quite practical meaning — a thin watch will be useful for those who wear narrow sleeves with tight-fitting cuffs.