Model "31-N" Low Press Reducing Gas Service Reg. Graphite/Nbr Gasket; 1" Body Size,No.3 (0.1875") Orifice; Cf3m Body & Lower Case,Wcb Spring Chamber,Arrangement/Position 1,;Standard Construction Includes Internal Sensing Unless Option - "Es";Is Specified; S40v Trim: 316lSST Internals,Fluorocarbon Elastomer (Fkm) Seat &;Diaphragm With Reinforcing Core,Glass Filled Nylon Load Ring,;No Oxygen Service; Npt Screwed; 8.0-12.0" Wc Range Spring