Union Butterfield 1567(NPTF) High-Speed Steel Pipe Tap, Interrupted Thread, Uncoated (Bright) Finish, Round Shank With Square End, 1/2"-14 Thread Size Pipe tap cuts threads in pipes and pipe fittings NPTF (National Pipe Taper Fuel) threads for leak-free seals without the use of sealants Straight flutes to cut threads in through holes and blind holes Interrupted thread for more lubrication and better chip disposal than continuous thread Round shank with square end helps to minimize rotation in the tool holder