Professional Diamond Hole Cutter: With Special design of diamond brazed For porcelain, glass, marble, ceramic, rock and granite etc. High Quality Hole Drilling: Made from carbon steel with diamond blade ideal for drilling clean and accurate holes and cut a perfect circles with these tools Longer Service Life: Heavy duty hole saws gives superior performance, Durability is more than 8 times Tips: Electroplated diamond coating will wear off if the tool gets too hot. Never let your drill bit run dry. Package Include: 6mm, 8mm, 10mm, 12mm, 16mm, 20mm, 22mm, 25mm, 30mm, 38mm, 50mm diamond hole saw drill bit set of 11 pack Product description Specifications: Material: Carbon Steel 11pcs 6mm-50mm Diamond Hole Saw Drill Bit Set Features: --This diamond coated core drill bit removes a complete circle from glass, tiles, marble, granite, ceramic or other materials Note: If you smell burning, back off! Either your speed is too high or the pressure you're applying is too much. You're drill bit should never be hot to the touch, not even warm. Please: Always use water for lubrication., otherwise the diamond core drill will burn. Can be used with a standard electric drill. make a half round mark and then hold drill straight. Reduced drill speeds, low drill pressure and increased use of water lubrication will extend drill bit life considerably. Use Coolant. Minimum pressure. The general rule is the smaller the diameter of your drill bit, the faster drill speed you can use. The harder your material, the slower drill speed you should use. The shank diameters of the Diamond Drill Bits are: The shank diameter of 6mm diamond drill bit is 6mm. The shank diameters of 8mm to 25mm diamond drill bits are 8mm. The shank diameters of other diamond drill bits are 10mm. Package include: 11Pcs * Diamond Brazed Drill Bit