MODEL "123" BACK PRESS RELIEF REGULATOR,TFE GASKETS 1/2" SIZE; BRONZE BODY & SPRING CHAMBER (OPT-5), CRYOGENIC CONSTRUCTION OPT-55: CLEANED FOR OXYGEN SERVICE PER SPEC #S-1134; B5 TRIM: BRASS WITH TFE SEAT,PHOS.BRONZE DIAPHRAGM; NPT SCREWED; 120-245 PSIG SST RANGE SPRING;