Unibit step drill bit, 11 increments 3mm to 13mm Ideal for drilling holes into thin materials such as steel, stainless steel, copper, brass, aluminum, plastic and laminates . Sizes: 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm and 13mm. Material: HSS Finish: Titanium coating Single-flute cutting edge for greater control through steps Hex shank prevents slipping in drill chuck