Model "CA-2" Back Pressure Relief Regulator; 1/2" Globe Design,Side Inlet,Side Outlet; Bronze Body & Spring Chamber; S2 Trim: 303SST Metal Seat,302SST Diaphragm; Npt Screwed; 150-250 PSIG Range Spring; Cryogenic Construction (Opt-5); Opt-56: Special Clean Per Spec #S-1542