1" Female Pipe Thread, Boiler Air Scoop, For Hydronic Systems, Entrapped Air In The Hot Water Heating System Piping Is Dispersed By The Internal Agitator Of The Air Scoop As The Water Is Re-Circulated Within The Heating System Piping, Provides Quiet Efficient Operation Of The Hot Water Heating System, Complete & Continuous Purging & Venting Of Air In The Heating System When Installed With The Duo Vent Float Vent Or FV-M1 Automatic Air Vent Valves, Cast Iron Construction, Tapping For Expansion Tank & Air Vent, Duo Vent Or FV-M1 Vent Valves.