Model 345 Rev B Pressure Reducing Regulator; 1/2" Line Size; Stainless Steel Body With Bronze Spring Chamber; S3 Trim: 316 Stainless Steel With PTFE Seat, Fluorocarbon Elastomer O-Rings, Graphite/NBR Cylinder Gasket; NPT End Connections; 50-150 PSIG Range Spring; OPT-56: Clean For Non-Oxygen Service Per Cashco Specification S-1542