HACKMASTER(R) RECIPROCATING BLADES AMERICAN SAW Shatterproof Hackmaster R is a general purpose reciprocating blade that cuts almost anything: conduit, nail-embedded wood, composition materials, steel, etc. Bi-metal blade cuts fast and easily because its teeth are electric furnace hardened. Fatigue-resistant alloy steel back is electronbeam welded to a high speed cutting edge. 5 per carton. Size: 4" x 3/4", Teeth per in: 18