Model 123 Rev C Back Pressure Regulator, PTFE Gaskets; 1/2" Line Size; LCC Steel Body With LCC Steel Spring Chamber; S40B Trim: 316 Stainless Steel With Metal Seat, Special Neoprene (BC) Diaphragm; NPT End Connections; 120-245 PSIG Stainless Steel Range Spring; OPT-40: Construction Per NACE Standard MR0175