MODEL "2171" CRYOGENIC BACK PRESSURE RELIEF REGULATOR,TFE GASKETS 1/4" SIZE, ANGLE DESIGN (TWO SIDE INLETS - BOTTOM OUTLET); 316L SST BODY, BRONZE SPRING CHAMBER OPT-55: CLEANED FOR OXYGEN SERVICE PER SPEC #S-1134; S1 TRIM: 316L SST METAL SEAT,302SST DIAPHRAGM; NPT SCREWED; SPECIAL RANGE SPRING; PER SPQ NUMBER 53725 200-650 PSIG RANGE; SPECIAL CLEAN PER CASHCO SPEC #S-1134 (OPT-55); HI-PRESSURE SPRING CHAMBER (OPT-80