Tool-Flo 1271002 Helical Flute Thread Mills; Material: Carbide ; Thread Size (Inch): 7/16-20 - 1/2-20 ; Thread Type: Internal ; Shank Diameter (Decimal Inch): 0.3120 ; Cutting Diameter (Decimal Inch): 0.2800 ; Length Of Cut (Decimal Inch - 4 Decimals