This Draper stepped drill bit allows you to drill multiple sized holes with one bit The Draper 71220 Step Drill Bit allows you to drill multiple sized holes ranging from 4-20mm with one bit. Use it in steel, brass, copper, aluminium, wood and plastics. Features: Step drill bit with 2mm increments perfect for drilling into steel, brass, copper, aluminium, wood and plastics Manufactured from good quality high-speed steel, correctly hardened for a longer life Drill steps marked at graduations: 4, 6, 8, 10, 12, 14, 16, 18, 20mm Specification: Range: 4-20mm