Model BQ Rev A Back Pressure Regulator, Graphite/NBR Gaskets; 1/4" Inlets,1/2" Outlet; Stainless Steel Body With Stainless Steel Spring Chamber; S0 Trim: 316 Stainless Steel With Metal Seat, PTFE Coated 302 Stainless Steel Diaphragm; NPT End Connections; 20-75 PSIG Range Spring