1/8-27 NPT Hex Rethreading Die for Taper Pipe Threads- Carbon Steel Size: 1/8-27 NPT For repairing worn or damaged NPT taper pipe threads. The dimension across the flats is not designed for any specific holder. Can be used with an adjustable wrench. For rethreading standard "1/8" Pipe" - the actual thread dimension is greater than 1/8".