Spherical Rotary Burr: Head Diameter: 40mm, Handle Length: 68mm, Handle Outer Diameter: 25mm Durable: Grinder bit made of heat-treated tungsten carbide that lasts 10 times longer than HSS, suitable for machining various types of metal materials, including hardened steel ≤ HRC65 Versatile: Sanding accessory widely used for carving, bowl cutting, model engineering, wood carving, bowl gouge, casting, deburring, grinding, sculpting Function: Wood carving wheels have a very rough coating to quickly remove void while maintaining a relatively smooth finish.