Tonsiki 10 Pieces 20mm Sharp Vented Rotary Diamond Cutting Discs Disks Kit Blade Cutting Sheet + 2 Mandrel Dremel Tools for Gemstones,Metal,Glass,Ceramics,Tiles Size:Bar by 3 mm / 0.1 degrees (38 mm diameter length L / s. 1.5);Saw blade diameter of 20 mm / s. by 0.9"; Great tools for DIY, craft work, jewelry making or silver smithing. These discs are super thin making them perfect for making slots and slits Ideal For Cutting: Gem stones, metal, glass, ceramics, porcelain, tiles, carbide, rocks.etc These discs are coated on both sides as well as around the edge Please note: The rational use of this product, try not to use in the excellent metal. Use the process, please add water, moderate to reduce the friction temperature.