hese drill bit kits are made of upgraded carbon steel with smooth nickel plating surface to resist corrosion, sharp and durable without edge collapseCoated with high quality diamond to improve drill efficiency and creates a sharp, high precision and smooth cut.1/4 inch, 5/16 inch, 3/8 inch, 1/2 inch, 16/25 inch, 5/8 inch, 11/16 inch, 3/4 inch, 7/8 inch, 1-1/5 inch,to meet various drill needs.Diamond drill bit set kit are used to drill Glass, Porcelain, Ceramic, Marble, Granite Stone, Bottles, Pots.Color: silverMaterial: carbon steelPackage Contents:1set diamond drill bitsOnly 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.