3/16" shank, 0.135" cutting diameter, 4 Flutes, 0.070 neck diameter, 1" reach depth, 2-1/2" overall length. Use for milling #10 diameter threads or larger. Internal or external threads from 20-56 TPI. Solid Carbide. Made in USA Please Note: These are not 3/8" cutting diameter Endmills. The 3/8" means you can thread mill an internal thread as small as 3/8"-16.