Irwin 88816 Speedbor 1-Inch by 6-Inch Spade Drill Bit N/A Imported Cutting material is steel Cutting diameter 1" Overall length 6" 1" diameter and 6" long Micro-groove point and cutting edges with extended spurs for faster, cleaner boring action Forged in one piece from Irwin's own special grade tool steel Heat-treated full length for extra overall strength For 1/4" and larger electric drills