MK Morse (1 pack of 5) Master 12" x .042", TPI18, Cobalt Bimetal Reciprocating Saw Blade. Master Cobalt bimetal reciprocating saw blades are the best blades in the world for cutting wood and metal, including steel, stainless steel, iron, sheet metal and pipe. Master Cobalt technology was developed and tested in the Morse Technology Center, using many variables affecting blade life. The result is a unique combination of features that has tripled the life of standard reciprocating saw blades. These are the longest lasting reciprocal blades available. (403986)