Details: From the Manufacturer Dewalt DW3742C 14 Pc T-Shank Jig Saw Blade Set with Case comes with five different sets of blades. The 6 and 10-tooth per inch blades are 4-inches long and are made with HCS material. The 12-teeth per inch blades are 3-1/2-inches long and are also made with HCS material. The 18 and 32-teeth per inch blades are 3-inches long and made with Bi-Metal material. These blades are for wood and metal applications.