Model "31-N" Low Press Reducing Gas Service Reg. Graphite/Nbr Gasket; 1" Body Size,No.4 (0.250") Orifice; Sales Kit B; Wcb Body,SST Lower Case,Wcb Spring Chamber,Arrangement/Position 2,;Standard Construction Includes Internal Sensing Unless Option - "Es";Is Specified; S40n Trim: 316lSST Internals,Buna-N Seat & Diaphragm With Reinforcing;Core,Glass Filled Nylon Load Ring,No Oxygen Service