These Dremel emery cut-off wheels are suitable for metal including hardened steel. They are compatible with Dremel cut-off wheels with mandrel 402. They're 51mm wide 32mm in diameter. Cut-Off Wheels, perfect for slicing and cutting in metal, wood and plastic. Features and Benefits Cut-off wheels make it easy to cut of slot bolts, screws, sheet metal, thin wood, and plastic. Fibreglass reinforced cut-off wheels (426) and heavy duty wheels (420) are perfect for tough applications. Notes: Do not attempt to grind or sand. Max. speed: 35,000rpm. Shank diameter: 3.2mm. Max. working depth: 24mm. These wheels cut only along their edges. Use Dremel cut-off wheels with mandrel 402.