SD89158 – ASADA Dies HSS 1in – 2in NPT Pitch Threading Die Chasers. Other threading chasers available: BSPT, NPT, BSPS, Conduit, BSW, Metric, UNC, UNF, Asada Threading Oil is strongly recommended, Alloy material is for general purpose threading such as black or galvanised pipe and rod & HSS material is for stainless steels and high tensile steels.