1/2" Union Solder Inlet x 1/2" Female Pipe Thread Outlet, Boiler Feed Water Regulator, Bronze Body, Use To Fill The Boiler & System Piping With Water & To Maintain Water Pressure, Use To Provide Make Up Water To The System, Fast Fill Feature Is Used To Speed Filling & Purging Of Air From The Piping On The Initial Fill, Manual Purge Lever Included To Manually Force The Valve Open For Efficient System Purging, Stainless Steel Strainer Protects Valve Disc From Fouling, Tight Seating Check Feature.