This Diamond Glass Grinder Radius Edger Bit head combines a flat and radius (rounded) edger. Select this for mosaics or when working with exposed glass edges. Use the fine grit radius head to virtually eliminate chipping on decorative mirror edging. Standard 100 grit. Made with a patented diamond bonding process for extra long life. Fits Glastar G3, G4, G7, G12, G14 and all Inland Grinders.