Industry’s safest backing plates for grinding. Superior quality & unaffected by heat. Must use as stacked set, at least two sizes, one behind the other. Failure to do so will limit the life of the plates. Never use a backing plate without without first inspecting it for signs of irregularities such as fracture, excessive wear, nicks, or cuts at the edge or center hole. Do not exceed maximum of 6,000 RPM. Always wear safety glasses, face shield, and heavy gloves when grinding.