Irwin Tools 1837626 TORX T27 Impact Performance Series Power Bit, 3-1/2" These insert bits feature precision-tip geometry for superior fitment and reduced stripping Insert bit is made from heavy-duty, cold-forged, high-grade steel to withstand high-torque output Impact drivers provide these screwdriver bits with high durability and long life Power Groove is designed for compatibility with IRWIN Impact Performance Series magnetic screw-hold attachments These insert bits have a black oxide finish to resist corrosion and increase life