Model "DA8" Differential Back Pressure Regulator (Series VIII)-PDBPV; Body Size 2",Standard Diaphragm Construction; Carbon Steel Body & Carbon Steel Spring Chamber,1/8" Petcock;Vent; 17-4 Ph SST Trim, 316l SST Cage, Pa Seat, Nbr Diaphragm,;Nbr Static Seal, SST/Tfe U-Cup Dynamic Seal; 300 Lb Raised Face Flanges; 30-90 PSId Range Spring; Large Internal Sensing, Reverse - Flow To Open Direction; Opt-65a: Double Tapped Spring Chamber,1/4" Npt