Union Butterfield TN1500(UNC) High-Speed Steel Hand Tap, TiN Coated, Round Shank With Square End, Plug Chamfer, 5/16"-18 Thread Size Hand threading tap with straight flutes cuts threads in through holes and blind holes Titanium nitride (TiN) coating combines hardness with low friction for extended tool life and faster cutting Available in UNC (Unified Coarse) and UNF (Unified Fine) right-hand thread options for different applications High-speed steel is compatible with a variety of materials Round shank with square end allows tap to be used in hand or power-driven applications