Model D Rev D Pressure Reducing Regulator For General Service; 1" Line Size; Stainless Steel Body And Spring Chamber; S40 Trim: 316 Stainless Steel Metal Seat And Neoprene (BC) Diaphragm; NPT Threaded End Connections; 10-40 PSI Range Spring; Polyethylene Vented Spring Chamber Plug; Opt-40SST: Construction Per Nace Standard Mr0175