Model DA2 Rev E Differential Pressure Reducing Regulator; 1/2" Line Size, OPT-81: Full Diaphragm Support Construction; Stainless Steel Body With Stainless Steel Spring Chamber, 1/8" Petcock Vent; P2 17-4PH Stainless Steel Trim, 316L Stainless Steel Cage, Polyurethane Seat, Neoprene Diaphragm, BUNA-N Static Seal, Stainless Steel/PTFE U-Cup Dynamic Seal; OPT-32: Schedule 80 Plain End Extended Nipple End Connections; 5-20 PSID Range Spring; Internal Sensing; OPT-65A: 1/4" NPT Double Tapped Spring Chamber