The SMG Ridgid Pipe Threading Dies Alloy 1″-2″ NPT are made from special pre-heat-treated steel, Long life, and easy threading, Available in two grades alloy and HSS, 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, The life of the dies is greatly affected by the quality of cutting oil used, Asada Threading Oil is strongly recommended, Many sizes available: BSPT, NPT, BSPS, Conduit, BSW, Metric, UNC, UNF, Dies to suit Ridgid Size: 1″-2″ NPT