Model "DA8" Differential Back Pressure Regulator (Series VIII)-PDBPV; Body Size 1/2",Opt-81: Full Diaphragm Support Construction; Cf3m Body,316l SST Spring Chamber,1/8" Petcock Vent; 17-4 Ph SST Trim, 316l SST Cage, Pa Seat, Epr Diaphragm,;Epr Static Seal, Tfe Cap Seal, W/Epr Energizer Dynamic Seal; Npt End Connection; 1-10 PSId Range Spring; Internal Sensing, Reverse - Flow To Open Direction; Opt-65a: Double Tapped Spring Chamber,1/4" Npt