Tool-Flo 1271394 Helical Flute Thread Mills; Material: Carbide ; Thread Size (Inch): 5/16-24 - 3/8-24 ; Thread Type: Internal ; Shank Diameter (Decimal Inch): 0.3120 ; Cutting Diameter (Decimal Inch): 0.2600 ; Length Of Cut (Decimal Inch - 4 Decimals