Total number of items
The total number of items in the set. In this case, both the actual
bits and end heads are taken into account, as well as additional accessories such as an adapter, a bit holder, etc.
The more items in the set, the wider its possibilities. However, note that the specific composition of the kit may be different, so when buying it is worth specifying not only the number of items, but also their specific types.
Landing square
The size of the square of the bits / sockets supplied in the kit.
The seat square is a standard fixture used in bits and sockets. For installation on a bit holder, ratchet, etc., the size of the square must correspond to the size of the seat. However, complete fixtures (like the same bit holder) by definition have fasteners of the right size, so you have to pay attention to the size of the square mainly if you plan to use nozzles with third-party tools.
Also note that the overall dimensions of the complete bits / heads can be estimated from the landing square: the larger the square, the larger the nozzles. For example, in 1/2" sockets, the size starts from 8 – 10 mm, and in 1" sockets — from 24 mm.
T bits (Torx)
The total number
of Torx bits supplied in the set.
The Torx tip has the shape of a six-pointed star. This provides a larger area of contact with the fastener than flat and cross bits, and allows you to work with higher forces.
12-points M bits (Spline)
The total number
of Spline bits supplied in the set.
Spline tips are star shaped with 12 points. This shape provides a very large area of contact with the spline and prevents the bit from being pushed out of the spline, making it possible to work with high forces.
M bits sizes
The sizes of the Spline bits included in the set, and the number of bits of each size.
For the bits themselves, see above. The size is indicated by a number indicating the width in millimetres — for example, M12 or M14. If there are several bits of the same size, their number may be specified after the size, but Spline type bits are usually supplied one of each size.
Adapter
The number of
adapters (adapters) supplied in the kit.
Adapters can have different purposes. So, in some sets, bits have hex shank, and the adapter is used to secure such tips in a square seat. Others use adapters from one seat square size to another. The specific purpose of the adapters in each case should be clarified separately, but here it is worth saying that most often only one adapter is included in the kit — it is believed that this is quite enough for most cases. However, occasionally there are sets with both 2 and 3 adapters — they, accordingly, have more opportunities for choosing the method of connecting the nozzle to the tool.
Bit holder
The number of bit holders supplied in the set.
In most cases,
a bit holder is a kind of "extension" for bits of standard length, designed to be installed in a screwdriver (extended bits can be installed without a bit holder). On one side of this "extension" there is a seat for complete bits, on the other — a standard hex shank. In some cases, such a device can even be used as an improvised screwdriver if there is no full-fledged screwdriver handle at hand.
In addition, some manufacturers call bit holders adapters from a hexagonal bit shank to a landing square of one size or another.
There is rarely more than one bit holder, however, there are exceptions to this rule when holders have different shank sizes.
