Specification: Type: step drill Material: high-speed steel Case size:12.5*9.5*3.5cm Size: #1: 4-12mm 5 steps(4mm,6mm, 8mm, 10mm, 12mm) #2: 4-20mm 9 steps(4mm, 6mm, 8mm, 10mm, 12mm,14mm, 16mm,18mm, 20mm) #3: 4-32mm 15 steps(4mm, 6mm, 8mm, 10mm, 12mm,14mm, 16mm,18mm, 20mm, 22m, 24mm, 26mm, 28mm, 32mm) Features: Specifical step design, one drill for many sizes, very convenient. Cutting material: iron sheet, aluminum, insulation board, PVC plate wood thickness in 4mm.The hole with a drill can play a variety of. SELF STARTING - No need for a pilot hole. Automatically deburrs holes as you drill. Long Life True high speed steel. Nitriding to make it durable and run cooler. Includes protective padded aluminum case. Package Included: 1x 4-12mm drill 1x 4-20mm drill 1x 4-32mm drill 1x case