M2 high speed steel cutting edge welded to a shatter resistant spring steel back. Cuts up to 1 5/8" deep. 4/6 Vari Tooth design for aggressive cutting action and reduced vibration. 3/16" thick heavy duty backing plate is more durable than stamped backing cups and eliminates need for torque driving plate. Use for heavy duty cutting in stainless and mild steel, cast iron, copper, brass, aluminum, plastics, wood, and composition board.