Maid-O-Mist #72 Hot Water Automatic Air Vent Valve 1-1/4 x 1/2 in.
The no. 7 series Auto-Vents air eliminators are made of brass and equipped with a self-closing, float-operated valve. No air chamber is required. The vent is regularly fitted with a patented cap that may be used as a check in case of a leak caused by core sand or scale.