Union Butterfield 3300(UNC) High-Speed Steel Thread Forming Tap, Uncoated (Bright) Finish, Round Shank With Square End, Bottoming Chamfer, H2 Tolerance, 2-56 Thread Size Cold-forms threads in through holes and blind holes without producing chips Rol-Form design includes oil grooves in larger sizes to improve coolant flow Available in UNC (Unified Coarse) or UNF (Unified Fine) right-hand thread options for different applications High-speed steel for compatibility with a variety of materials Round shank with square end helps to minimize rotation in the tool holder