Model 123 Rev C Back Pressure Regulator, Graphite/NBR Gaskets; 1" Line Size; Stainless Steel Body With Stainless Steel Spring Chamber; S40T Trim: 316 Stainless Steel With PTFE Seat, Fluorocarbon Elastomer (FKM) Diaphragm; OPT-30: Mates With ASME 150 Raised Face Flanges; 30-80 PSIG Range Spring; OPT-40SST: Construction Per NACE Standard MR0175