IRWIN Tools 1877491 Impact Performance Series 6-Point Deep Well Socket Bit, 18mm, 3/8-Inch Square Drive Built for maximum durability and long life with impact drivers Six-point deep wells with recessed corners drive torque across the flats for more secure fit and long life Made from heavy-duty chrome molybdenum steel for maximum durability and long life with impact drivers Thin wall construction increases access to tight spaces Manufactured with heavy-duty, cold-forged, high-grade steel to withstand high torque output