IRWIN Tools 1882428 Impact Performance Series Double-Ended Screwdriver Number-1 Square Power Bit with 4-Inch Length Built for maximum durability and long life with impact drivers. DoubleLokTechnology ensures both ends of bit lock securely 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