[LARGE SPACE HOLE] This glass hole punch placed on the drill bit facilitates the entry of cooling water and the escape of chips and other particles from the drilling. Facilitates the drilling process. [EXTRAORDINARY SHARPEN] Each diamond has a smooth and exact finish that reduces incision resistance and drilling pressure, increases the sharpness and effectiveness of water lubrication. Excellent for making clean and precise holes in glass or ceramic and prolong considerably useful drill bit. [HARD END] These diamond drill bits are made of industrial carbon steel with nickel coated body to resist corrosion. A thick diamond layer on top offers superior cutting strength for maximum drilling results. [WIDELY USE] 5 different size drill bits (4 mm / 0.16 inch, 6 mm / 0.24 inch, 8 mm / 0.31 inch, 10 mm / 0.39 inch, 12 mm / 0.47 inch) included with this glass drill bit set to meet various demands. For drilling glass, tiles, porcelain tiles, ceramic tiles, brick and stone., Weight: 0.05952481074 pounds, Manufacturer: Rtxbvg