Feature●The gears is made from HSS and the rigidity varies from the hole saw has a twist drill bit inside, which is undetachable.●64HRC to 65HRC. Sharp gears and anti-cutting with lower consumption make the product a long service life.●Carbide teeth for fast cutting of clean, round holes.Suitable for hand held electric drill, stand motor-driven drilling machine and mobile ribbon type magnetism drilling machine.●Cuts quick, precise holes in stainless steel, mild steel, iron, copper and brass.Can drill about 20mm depth for the wood, and can drill about 5mm for the stainless steel●Size of these 15pcs hole saw: 15mm/0.59", 16mm/0.63", 18mm/0.71", 20mm/0.79",21mm/0.83", 22mm/0.87", 25mm/0.98", 26mm/1.02", 28mm/1.10", 30mm/1.81", 35mm/1.38", 40mm/1.57", 45mm/1.77", 50mm/1.97", 53mm/2.09".Description