IRWIN Tools 1899875 Impact Performance Series Screwdriver Power Bits, 4mm Hex, 2-Inch Length, 10-Pack Built for maximum durability and long life with impact drivers Precision tip geometry delivers superior fitment, reducing stripping and cam-out Power Groove designed for compatibility with IRWIN Impact Performance Series Magnetic Screw-Hold Attachment Manufactured with heavy-duty, cold-forged, high-grade steel to withstand high torque output Black oxide finish resists corrosion and increases life of extractor