1. The model of a flat-blade screwdriver is expressed as bit width shank. For example, 275mm means that the width of the cutter head is 2mm and the length of the rod is 75mm (not the full length).
2. The model of the Phillips screwdriver is expressed as the size of the head the shank. For example, 275mm, it means that the cutter head is No. 2, and the length of the metal rod is 75mm (not the full length). Some manufacturers use PH2 to represent 2, which is actually the same. You can roughly estimate the size of the cutter head by the thickness of the cutter shank, but the industry is distinguished by the size of the cutter head. The thicknesses of the metal rods corresponding to the models 0, 1, 2, 3, and 4 are roughly 3.0mm, 4.0mm, 6.0mm, 8.0mm, and 9mm.
