hese drill bit kits are made of upgraded carbon steel with plating surface to resist corrosion, sharp and durable without edge collapse Coated with high quality diamond to drill efficiency and creates a sharp, high precision and 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 drill needs. Diamond drill bit set kit are used to drill Glass, Porcelain, Ceramic, Marble, Granite Stone, Bottles, Pots. Color: silver Material: carbon steel Package Contents: 1set diamond drill Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.