Model BQ Rev A Back Pressure Regulator, Graphite/NBR Gaskets; 1/2" Inlets,1/2" Outlet; Ductile Iron Body With Ductile Iron Spring Chamber; S40 Trim: 316 Stainless Steel With Metal Seat, Neoprene (BC) Diaphragm; NPT End Connections; 5-15 PSIG Range Spring; OPT-1: Closing Cap