Step Sizes - 10, 15, 20, 25, 30, 35, 40, 45 mm For workpieces with hardness less than 25° - Carbon steel, thin iron plate, insulation board, PVC board, wooden board, with thickness less than 5 mm Anti-slip - Triangular shank: diameter - 12 mm; length - 25 mm 【More stable and even cutting】 - Two flutes spiral groove design, automatically chamfers the hole to clean the drill bit Chamfering, knocking, drilling or enlarging holes - Step drill bits can be used for chamfering, knocking, drilling or enlarging holes. Widely used for cutting holes in a variety of materials like plate, aluminum, insulation board, PVC, wood Specifications: Color: Black (as shown) Material: High Speed Steel Scop: Thin iron plate, aluminum, insulation boards, PVC boards thickness 4 mm in wood. Type: 10-45mm(10,15,20,25,30,35,40,45mm), Shank: 25 x 12mm Total Size: 45 x 100mm Package Included: 1 x 10-45mm Twist Drill Bit