This WorkPro Square Bit Set- 5 Piece can optimized shock zone for impact driver use,making of S2 steel with heat treatment for maximum strength and durability. Includes: 3 piece- 2 inch bits and 2 piece- 3.5 inch bits. This Bits set ideal for most household projects,each bit has sandblasted finish for corrosion resistant. Heat-treated and tempered S2 tool steel absorbs shock, reisist twisting and cam-out for superior tool life. The bits have special non-slip grooves for better grip on screw face. Precisely and automatically machined bit tips to ensure accurate size, chamfered bit ends insert smoothly into fasteners and protect both bits and fasteners from damaged edges.