Model "1164" Back Pressure Relief Regulator,Aramid/Sbr Gaskets; 1-1/2" Size; Ductile Iron Body,Cast Iron Spring Chamber; S0 Trim: 316SST Metal Seat,Tfe Coated 302SST Diaphragm; Npt Screwed; 70-150 PSIG Range Spring; Opt-25: 1/4" Npt Spring Chamber Vent Tap; Opt-56: Special Clean Per Spec #S-1542