Model "31-N" Low Press Reducing Gas Service Reg. Graphite/Nbr Gasket; 1/2" Body Size,No.2 (0.125") Orifice; 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; Npt Screwed; 11.0-16.0" Wc Range Spring