Ingersoll Rand P4FS-20 Air Reciprocating Saw Blades come as a bulk pack of 20, 4”, 32 TPI fine blades. The bi-metal saw blades enhance overall cutting performance. Bi-metal technology is a solid state diffusion process that applies high speed steel to both edges of the backing material, increasing the blade contact area by 170%. This, along with a new tooth profile that generates smaller but more chips, reduces the frictional heat that is generated during the cutting process. P4FS-20 saw blades can be used with all standard 1/2" shank air reciprocating saws. For more than 100 years, Ingersoll Rand's advanced engineering, manufacturing, and service models have set a standard of excellence; Trust Ingersoll Rand to help you complete your work faster and easier than ever before.