HSS for added wear resistance & better lubricity of tool surface which increases tool life & productivity. 18 piece set in metal index. Includes the following tap sizes with their corresponding tap drill: (Tap Sizes: 6 - 32, 8 - 32, 10 - 24, 10 - 32, 1/4" - 28, 5/16" - 18, 3/8" - 16, 7/16" - 14, 1/2" - 13), (Dill Sizes: #36, #29, #25, #21, #7, F, 5/16", U, 27/64")
