Model 4381 Rev C Pressure Reducing Regulator For Standard Service; 1/4" Line Size; 316L Stainless Steel Body With Stainless Steel Spring Chamber; S40C Trim: 316L Stainless Steel With PTFE Seat, Neoprene (BC) Diaphragm; NPT End Connections; 5-30 PSIG Range Spring; OPT-4: Stabilizer (Recommended For Gaseous Service Only); OPT-25S: Screen For Spring Chamber Vent, Includes OPT-25: 1/8" NPT Spring Chamber Vent Tap; OPT-86: Outlet Pressure Gauge (Includes OPT-85: Outlet Body Gauge Port); OPT-40SST: Construction Per NACE Standard MR0175