Jingling 0.5mm Diamond Coated Hole Saw Drill Solid Bits Cylindrical Head Grinding Needle Lapidary Carving Jewelry Tools for Stone Pack of 30Pcs Product use:apply to stone carving, jade carving, bone carving, egg decorating, glass carving etc. Used for sculpturing, dressing, precision grinding and internal grinding carbide in ceramic, glass, precious stone, alloy and many the abrasive materials Head Diameter:0.5mm; Shank Diameter: 2.35mm (3/32") Product Name: Lapidary Diamond Drill Bits, Diamond Drill Bits for Stone Jewelry Can be installed on the electric grinder,hanging mill and hand electric drill (not included here).