Square drive size
The size of the "seat" for which the socket heads included in the package are designed (see below), in other words, the size of the square hole on the back of the head used for installation on a ratchet, wrench or other similar tool. Accordingly, the tool for working with heads supplied in the kit has the same dimensions of the landing square; and in the absence of such tools in the kit, data on the size of the heads will be useful for its selection.
There is a generally accepted standard for these sizes, providing for the designation in fractions of an inch — from 1/4 "to 1". Thanks to this, heads and tools from different sets can be quite compatible — just matching in size is enough. Most often in modern hand sets there are options in 1/4 "and 1/2", a little less often — 3/4" and 3/8". Some sets include several variants of the landing square at once.
Socket heads sizes (E-profile)
Working size range of E-profile sockets (see above) supplied with the kit. This parameter allows you to evaluate how the heads fit the dimensions of the fasteners with which they are planned to be used.
Dimensions
The dimensions of the entire set, namely the case, lodgment, cassette, etc. storage accessory (see paragraph above) with tools installed inside. Allows you to understand how much space the model will occupy and whether it can be placed in a complete set in one place or another.
