Boiler Feed Water Pressure Regulator, 1/2" Female Pipe Thread Inletand Outlet With 1/2" Female Pipe Thread Bottom Connection For Installation Of Expansion Tank, Fills The Boiler & System Piping With Water & Maintain Water Pressure, Provides Make Up Water To The System In The Event Of System Leaks, Fast Fill Feature Speeds Filling & Purging Of Air From The Piping On The Initial Fill, Manual Purge Lever Included, Stainless Steel Strainer Protects Valve Disc From Fouling, Tight Seating Check Feature.