Model D Rev D Pressure Reducing Regulator For General Service; 1/2" Line Size; Bronze Body And Spring Chamber; BK Trim: Brass With Fluorocarbon Elastomer (FKM) Seat And Diaphragm; NPT Threaded End Connections; 10-40 PSI Range Spring; Opt-4: Piston Stabilizer For Gaseous Service; Polyethylene Vented Spring Chamber Plug