Model 123 Rev C Back Pressure Regulator, PTFE Gaskets; 1" Line Size; Sales Kit B; Stainless Steel Body With Stainless Steel Spring Chamber, For Temperatures Down To -50°F, OPT-55: Cleaned For Oxygen Service Per Cashco Specification S-1134; S40C Trim: 316 Stainless Steel With PTFE Seat, EPDM Diaphragm;