Plug Chamfer - Fractional Sizes - Gold & Black National Coarse & National Fine Tap Set in a Index Case. High Speed SteelSizes: 1/4-20, 1/4-28, 5/16-18, 5/16-24, 3/8-16, 3/8-24, 7/16-14, 7/16-20, 1/2-13, 1/2-20