Model "123" Back Press Relief Regulator,Tfe Gaskets; 1/2" Size; Cf8m Body & Spring Chamber (Opt-36), Cryogenic Construction;Opt-55: Cleaned For Oxygen Service Per Spec #S-1134; S36 Trim: 316SST With Tfe Seat,302SST Diaphragm; Npt Screwed; 90-150 PSIG SST Range Spring