Irwin 10231 Unibit #1 High Speed Steel Step Drill Bit 1/8" to 1/2" (13 Steps - 1/32" increments) by Irwin Single-flute cutting edge for greater control through steps Hex shank prevents slipping in drill chuck New SpeedPoint tip penetrates faster than previous Unibits and prevents walking Ideal for drilling holes into thin materials like stainless steel, copper, brass, aluminum, plastic Self Starting - 1/8" Maximum Material Thickness