Model 31-N Rev A Low Pressure Reducing Gas Regulator; 3/4" Body Size, #2 (0.125") Orifice; Sales Kit B; Carbon Steel Body, Stainless Steel Lower Case, Carbon Steel Spring Chamber, Arrangement/Position 4, Internal Sensing Unless External Sensing Option Is Specified; S40N Trim: 316L Stainless Steel Internals, BUNA-N Seat And Diaphragm, Glass Filled Nylon Load Ring;