Model 123 Rev C Back Pressure Regulator, Graphite/NBR Gaskets; 1/2" Line Size; Bronze Body With Bronze Spring Chamber; S5 Trim: 316 Stainless Steel With 416 Stainless Steel Metal Seat, Fluorocarbon Elastomer (FKM) Diaphragm; NPT End Connections; 40-100 PSIG Range Spring