4-22mm HSS hex hole cutter cone step drill bit. Its step from 4mm to 22mm: 4mm,6mm,8mm,10mm,12mm,14mm, 16mm,18mm,20mm, 22mm. Step: 4-22mm (4,6,8,10,12,14,16,18,20, 22mm). Can drill in the thin iron plate, aluminum insulation board, PVC board with 5mm thickness.
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