While most screwdriving bits are simply compatible with impact drills and drivers, Irwin® Impact Performance Series™ fastener drive bits are engineered for maximum durability and long life with impact drivers. These bits are forged* rather than milled, so they fit fasteners more precisely, which reduces stripping and increases the life of the bit itself - Irwin® Impact Performance Series™ bits have three times longer life than traditional bits. Manufactured with heavy duty, cold forged, high grade steel, they'll withstand extremely high torque output. Plus, a black oxide finish resists corrosion and increases the life of the bit. Irwin® Impact Performance Series™ Drill/Drive Set, 32 Piece, For Use With: Impact Drills and Drivers, 1/4 in Shank, Cold Forged High Grade Steel, Black Oxide