Irwin 3018011 Speedbor 29 Bit 1/16-Inch to 1/2-Inch Twist Drill Bit Assortment in Metal Index High performance metal drilling for portable drill users, works well on curved surfaces Revolutionary tip design stays sharper longer and drills up to 10 times faster than other leading drill bits Self-centering tip for clean entry and fast starts, stays sharp longer 1/16" through 1/2" by 64ths with 3/8" reduced shank Three flatted shank on 3/16" and above for better chuck grip