The Irwin UNIBIT HSS fractional self-starting step drill #5, 1/4 to 1-3/8 in, is ideal for drilling clean, smooth holes in mild steel, copper, bass, aluminum, plexiglass, wood and laminate. Crafted of HSS, it has a SpeedPoint® tip that guarantees fast starts and a single-flute cutting edge for drilling true, round holes with a precise step control for multiple sizes. Hole sizes are permanently laser-etched on the inside of the flute and will not wear away for easy identification throughout the life of the bit. The bit features a quick change hex shank that secures easily in the drill chuck.