Sizes: #4-40, #6-32, #8-32, #10-24, #10-32, #12-24, 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. About High Speed Steel Plug Taps: Used to make new threads or re-thread damaged and/or jammed threads. Hand taps are the most versatile taps for hand use, or for tapping under power. Hand taps are popular for use in general machine tapping or CNC tapping. They are also appropriate for tapping the vast majority of materials in through or blind holed conditions. Plug style taps are generally used in thru holes. About High Speed Steel Round Dies: For use in making new threads or re-threading existing threads. Good for most general purpose applications, offering a combination of hardness and toughness for wear resistance. Round die is chamfered on both faces. One side has a 2 to 3 thread chamfer for threading, the other side has a 1 to 1-1/2 thread chamfer for threading close to a shoulder. Adjustment is obtained by a fine pitch screw which forces the sides of the die apart, or allows them to spring together. The slot is beveled so that when the dies are used in a machine holder the adjusting screw can be removed and adjustment made by the adjusting screws in the holder.