Irwin Tools UniBit 3/16-Inch to 1/2-Inch Step-Drill Bit, 1/4-Inch Shank (10232) None Imported Single-flute cutting edge for greater control through steps SpeedPoint tip penetrates fast and helps prevent walking Hex shank helps prevent slipping in the drill chuck IRWIN Unibit step drill bits are ideal for drilling holes into thin materials, such as stainless-steel, copper, brass, aluminum, plastic and laminates Drills 3/16" - 1/2" holes in 1/16" steps 6 hole sizes Easy-to-sharpen, non-skid tip Single-fluted cutting edge 3 flatted shank Full lifetime warranty