Model D Rev D Pressure Reducing Regulator For General Service; 1/2" Line Size; Ductile Iron Body And Spring Chamber; S4N Trim: 416 Stainless Steel With BUNA-N (NBR) Seat And Neoprene (BC) Diaphragm; NPT Threaded End Connections; 10-40 PSI Range Spring; Opt-25S: Stainless Steel Vented Spring Chamber Plug