Irwin Tools Unibit #21 13/16-Inch to 1-3/8-Inch Step-Drill Bit, 1/2-Inch Shank (10221) None Imported Ideal for drilling holes into thin materials such as stainless steel, copper, brass, aluminum, plastic and laminates Single-flute cutting edge for greater control through steps Patented single-flute cutting edge gives the user a true round hole every time 3 faltted shank prevents slipping in drill chuck Pilot hole required