Carmex Thread Mills Solid Carbide - Fast Type - For Hard Materials - UN (UNC UNF UNEF UNS) - 5/16, 3/8 x 24 - MT3Carmex Thread Mills are precision solid carbide tools designed for fast, reliable thread milling in hard materials. This fast type mill supports UN, UNC, UNF, UNEF, and UNS thread standards, with cutting sizes in 5 16" and 3 8" and a 24 TPI pitch, all mounted on a robust MT3 shank for production grade rigidity. Size options: 5 16" and 3 8" cutting diameters with 24 TPI pitch, compatible with UN UNC UNF UNEF UNS thread forms. Shank and material: Solid