Model 31-N Rev A Low Pressure Reducing Gas Regulator; 1-1/2" Body Size, #6 (0.375") Orifice; Carbon Steel Body, Stainless Steel Lower Case, Carbon Steel Spring Chamber, Arrangement/Position 4, Internal Sensing Unless External Sensing Option Is Specified; S50N Trim: 316L Stainless Steel Internals, BUNA-N Seat And Diaphragm; OPT-30: Mates With ASME 150 Raised Face Flanges; 3.0-4.5" wc Range Spring