Union Butterfield 1528S(UNF) High-Speed Steel Hand Tap Set, Uncoated (Bright) Finish, Round Shank With Square End, 3-Piece (1 Taper, 1 Plug, 1 Bottoming Chamfer), H2 Tolerance, 4-48 Hand threading tap set with straight flutes cuts threads in through holes and blind holes Machine-screw tap sizes, in frequent demand for many industries and products Available in UNC (Unified Coarse), UNF (Unified Fine), or UNS (Unified Special) right-hand thread options for different applications High-speed steel is compatible with a variety of materials Uncoated (bright) tools have no additional surface treatment or coating, for use on a broad range of materials