Dremel silicon carbide Grinding Stone. Designed to grind and etch stone, glass, ceramics, porcelain and non-ferrous metals. One stone included. -One 84922 silicon carbide grinding stones included -Ideal for sharpening, deburring and general purpose grinding on harder materials -Designed to work well on stone, glass, ceramic, porcelain, gemstones and non-ferrous metals -Specially designed for working with conic and flat surfaces -Great for grinding and etching (User Tips) -Always remember to have a spare battery pack charged up so you don't have to quit working to recharge your battery and keep your cordless rotary tool charged up and ready to go. -For best results, insert the accessory bit all the way into the tool and then back it out slightly before tightening down. This provides plenty of shank for the collet or chuck to hold onto the bit.