3pc HSS Titanium Coated Spiral Flute Step Drill Bit ,4-12/20/32mm Drop forged, heat treated, high speed steel, fully polish Take the guessing out of drilling by supplying the proper depth for you 4mm to 32mm 15 Steps (4mm,6mm,8mm,10mm,12mm,14mm,16mm,18mm,20mm,22mm,24mm,26mm,28mm,30mm,32mm) 4mm to 12mm 9 Steps (4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm) 4mm to 20mm 9 Steps (4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm,18mm,20mm)