2-1/2 inch hole saw. M2 high-speed steel cutting edge welded to a shatter-resistant spring steel back. Cuts up to 1-5/8 inch deep. 4/6 vari-tooth design for aggressive cutting action and reduced vibration. 3/16 inch 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. Hole sawReinforced to cut stronger, last longer and resist tooth strippageThick backing plate with holes for drive pins resists damage due to high torqueHigh speed steel teeth resist breaking and offer extended lifeBi-metal2-1/2 in. diameterUse this hole saw with a 2L, 3L, 6L, 7L standard arbor or a 2L, 6L snap-back arbor.