6-Pack of extra course variable Pitch air Recip saw blade - 14/18 TPI. Ingersoll Rand 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, which will enhance the overall blade performance. Ingersoll Rand saw blades can be used with all standard 1/2" Shank air reciprocating saws.