【High Quality】Our diamond drill bits are made of carbon steel. Their thick diamond coating on the top provides superior cutting strength for optimal drilling results. Fine workmanship and very wear-resistant. 【Dimensions】10 pieces (8/10/12/14/16/18/20/22/25/50 mm). These different sizes meet your needs and help you in different places. 【Wide Application】This diamond drill bit can drill a complete circle on marble, ceramic, glass, tile, granite, slate, etc. It is ideal for drilling holes in glass, wood, tiles, bottles, blocks, pots, ceramics, slate, granite, light stone, etc. 【Elegant Design】Diamond coating optimizes performance and maintains a sharper edge than traditional carbide or bi-metal hole saws. The side holes of the diamond hole saw allow for easy chip removal. Drilling 【Attention】Can be used with a standard electric drill (not included). Please add water regularly when the diamond drill bits are working on glass or ceramic. Increased water absorption can extend the life of