#20 Unibit Hole-Enlarging Stairstep BitGet it all done with one when you choose Unibit® stairstep bits. Single-flute cutting edge provides precise depth control though all size steps. Shank's flat side surface ensures slip-free chuck lock-down. Blunt-tip, hole-enlarging bit may be used on stainless steel, copper, brass, aluminum, plastic, laminates and wood. Material(s): Steel.