Model "123" Back Press Relief Regulator,Tfe Gaskets; 1-1/2" Size; Cf8m Body & Spring Chamber (Opt-36), Cryogenic Construction;Opt-55: Cleaned For Oxygen Service Per Spec #S-1134; Special Trim; Special Seal Welded Tube End Adapters; 110-300 PSIG SST Range Spring; Special Bolting; With Closing Cap