MODEL "DA5" BACK PRESSURE REGULATOR (SERIES V)-BPV BODY SIZE 4",STANDARD DIAPHRAGM CONSTRUCTION; CF3M BODY, DUCTILE IRON SPRING CHAMBER; 17-4PH SST TRIM, 316L SST CAGE, PA SEAT, FKM DIAPHRAGM FKM STATIC SEAL, SST/TFE U-CUP DYNAMIC SEAL; OPT-56: SPECIAL CLEANING PER SPEC #S-1542