The IRWIN UNIBIT High-Speed Steel Fractional Self-Starting Step Drill #5, 1/4" - 1-3/8", is ideal for drilling clean, smooth holes in mild steel, copper, bass, aluminum, plexiglass, wood, and laminate. Crafted of high-speed steel, 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.