Model BQ Rev A Back Pressure Regulator, PTFE Gaskets; 1/2" Inlets,1/2" Outlet; Stainless Steel Body With Stainless Steel Spring Chamber, OPT-36: Cryogenic Construction; S36 Trim: 316 Stainless Steel With PTFE Seat, 302 Stainless Steel Diaphragm; NPT End Connections; 65-150 PSIG Stainless Steel Range Spring; OPT-25S: Stainless Steel Rain-Proof Bug Vent (Includes OPT-25: 1/4" NPT Vent Tap)