Thürmer Tools 1936Z01 is a three-piece step-drill set for sheet-metal work covering 3-14 mm (Ø6 mm shank), 5-20 mm (Ø8 mm shank) and 16-30.5 mm (Ø9 mm shank) hole diameters. The graduated cutting edges allow multiple hole sizes to be produced from a single tool with clean, burr-reduced results in thin steel, aluminium and plastic sheet. Suited to electrical panel building, HVAC and general fabrication.