'Thread Mill, Helical, Internal or External, 5/16, Thread Size 5/16 In.-20, Pitch 20 TPI, End Mill Material Carbide, Flutes 3, Length of Cut 0.6700 In., Overall Length 2-1/2 In., Polished, Shank Dia. 1/4 In., Thread Type UN, Nomenclature TM, For Use With -, Application All Types of Metals, Composites and Tough-to-Machine Materials'