Model D Rev D Pressure Reducing Regulator For General Service; 1/2" Line Size; Sales Kit B; Bronze Body And Spring Chamber; B4 Trim: Brass With PTFE Seat And Fluorocarbon Elastomer (FKM) Diaphragm; Opt-4: Piston Stabilizer For Gaseous Service; Opt-55: Oxygen Cleaning Per Cashco Specification S-1134