1/8" male pipe thread, automatic boiler air vent valve, provides automatic air venting for hot & cold water distribution systems, manual vent feature provides tremendous air elimination capability for fast venting of residential & commercial systems, duo vent utilizes a float to actuate the valve plug, once air is displaced & the system pressure is sustained the valve plug seals & prevents any water from escaping the system, maximum working temperature 240&degree. Fahrenheit, maximum working pressure 150 PSI, brass construction, suitable for gylcol systems.