Irwin 1837435 Phillips Impact Power Bit #1, 2 Inch OAL, Black Oxide, 2/Card Irwin Phillips Insert impact power bit is made of heavy-duty, cold-forged, high-grade steel for sustaining high torque output and has durable black oxide finish to resist corrosion. It has shank of diameter 1/4 Inch with a point of size 1 and measures 2 inches long. It is forged for better fitment that reduces stripping and increases life of bit 3X. Bit is ideally designed for maximum durability and longer life with impact drivers.