Characteristics: A diamond coated core drill removes a full circle from glass, tile, marble, granite, ceramics or other materials and only requires water lubrication. Available in a variety of sizes for many purposes. Can be used with a standard electric drill. Made of the highest quality metal with a diamond coating, it has high hardness, is wear-resistant and durable in use. Easy to use. Just start the hole diagonally and make a circular trace, then keep the drill straight. Always use grease (water), otherwise the diamond core bit will burn. Technical data: Material: metal with diamond coating Open Hole Size: 3mm / 0.12in, 4mm / 0.16in, 5mm / 0.20in, 6mm / 0.24in, 8mm / 0.31in, 10mm / 0.39 inch, 12 mm / 0.47 inch, 18 mm / 0.71 inch, 32 mm / 1.26 inch, 50 mm / 1.97 inch Total Length: Approx. 5 cm / 1.97 inch Quantity: 10 pieces Weight: Approx. 154g Package includes: 10 * Diamond Coated Hole Drill Bits