IRWIN 1837379 Insert Bit, #1 Drive, Square Recess Drive, 1/4 in Shank, Hex Shank, S2 Steel              IRWIN Impact Performance Series fastener drive bits are engineered for maximum durability and long life with impact drivers. These insert bits are designed with precision tip geometry so they fit fasteners more precisely, which reduces stripping and cam-out. 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.