Screwdriver divided into manual and electric by power source.
Approved by the head or heads divided and cross word.
There are many specifications and models, the industry which basically are based on the first batch for the. Its size there are two.

One is the metric, that is, we often say in mm units, and the other is English, and it is in.

As a unit, such as 1 / 4, 3 / 16, this figure is the metric size of the multiplier 25.

1, the word model is represented as head screwdriver width * Arbor. For example, 2 * 75mm, the width of said head

2mm, stroke length 75mm (non-full).
2, the cross-head screwdriver the size of the model is expressed as * Arbor. For example, 2 # * 75mm, then that head is 2,

Rod length of 75mm (non-full). Some manufacturers expressed by PH2 # 2, the actual for the same. You can

Arbor to roughly estimate the thickness of the size of the head, but the industry is to distinguish between head size. Model 0#, 1 #, 2 #, 3 # metal rod thickness roughly corresponds to 3.0mm, 5.0mm, 6.0mm.