Union Butterfield 1587(UNC) High-Speed Steel Spiral Flute Tap, High-Helix, Uncoated (Bright) Finish, Round Shank With Square End, Bottoming Chamfer, 8-32 Thread Size Spiral flute tap design pulls chips back from the tip of the tool and out of the hole to prevent clogging Spiral flutes for creating threads in blind holes Higher helix angle improves chip removal Available in UNC (Unified Coarse) or UNF (Unified Fine) right-hand thread options for different applications Round shank with square end helps to minimize rotation in the tool holder