MODEL "BQ" SALES B KIT FOR PRODUCT CODE: 1B4-1S17-11800000A; BACK PRESSURE RELIEF REGULATOR,GRAPHITE/NBR GASKETS; 1/2" INLETS,1/2" OUTLET; CAST IRON BODY & SPRING CHAMBER; S1 TRIM: 316SST METAL SEAT,302SST DIAPHRAGM;DIFFERENTAL CONSTRUCTION WITH CLOSING CAP (OPT-1+6);