M-42 Heavy Set Structural & Bundling Bi-Metal Dismantling For low speed machines. To Complete Part Number: Insert T.P.I. at XX. Insert Thickness at End. Bi-Metal Specialty Harder grade M-42 cutting edge with a special alloy backer steel for extreme resistance to dynamic strain. Ideal for extreme production applications. multi-piece cutting applications. and durability. Ideal for tubes, solids, and structural steel on back with special tooth design for superior shock resistance Tough, high speed steel edge attached to a quality steel Hi-Performance Production M-42 .