Harvey Tool 784314 | 1/4 3/8-18 Thread 0.3050" Diameter x 5/8" LOC x 5/16" Shank 4 Flute Uncoated Carbide Helical Flute Thread MillThis offering of Harvey Tool Thread Milling Cutters Multi Form is engineered to create internal and external National Pipe Taper (N,P. T. F.) threads. These helically fluted, solid carbide tools can cut both right and left hand threads. Cuts internal and external 60Degree National Pipe Taper (N. P. T. F.) threads Mills right hand and left hand threads Helical flutes Solid carbide CNC ground in the USA Product Specifications Cutter Diameter (Inch) 0.