Professional Diamond Hole Punch: With special brazed diamond design for porcelain, glass, marble, ceramic, rock and granite, etc. High Quality Hole Drilling: Made from carbon steel with diamond blade, ideal for drilling clean, precise holes and cutting perfect circles with these tools Long life: heavy-duty hole saws offer superior performance, durability greater than 8 times Tips: The electroplated diamond coating will wear off if the tool gets too hot. Never let your drill bit dry out Package Contents: 6mm, 8mm, 10mm, 12mm, 16mm, 20mm, 22mm, 25mm, 30mm, 38mm, 50 mm. 11Pcs Drill Bit Set Product Description Specifications: Material: Carbon Steel 11pcs 6mm-50mm Diamond Hole Saw Drill Bit set Features: This diamond coated core bit removes a full circle from glass, tiles, marble, granite, ceramic or other materials Note: If you feel the burn, step back! Either your speed is too high or the pressure you apply is too much. You should never be hot to the touch, not even hot. Please: Always use water for lubrication, otherwise the diamond core drill bit will burn. Can be used with a standard power drill. Make a half-round mark, then hold the drill straight. Reduced drill speeds , low drilling pressure and increased use of water lubrication will significantly extend drill bit life. Use coolant. Minimum pressure.< /p> The general rule is that the smaller the diameter of your drill bit, the faster the drill speed you can use. The harder your material, the slower drill speed you should use. Diamond drill bit shank diameters are: Diamond drill shank diameter of 6 mm is 6mm. Shank diameters of 8mm to 25mm diamond drill bits are 8mm. Shank diameters of other diamond drill bits are 10mm.< /p> Contents: 11 diamond brazed drill bits