Materials - These diamonds are made of high-speed steel drill bits that are and long lasting with sevice. Great fit - This diamond-coated Core drill removes a complete circle of glass, marble, ceramic, , ceramic or other. Like any standard bit, they are diamond coated for these purposes. Easy to use - This diamond drill has excellent quality and good performance, excellent cleanliness and precise holes. Colour: silver Material: metal alloy Size: 6-32mm Package Contents: 10 * Diamond Drill Bits Precautions - When using a diamond drill, use lubrication (water) or the diamond core Drill will burn. Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.