Air Vent 9.5 in. H X 17.1 in. W Black Plastic Automatic Foundation Vent

The vent has a bi-metal coil to open and close automatically without electricity. When the temperature reaches 70 degree Fahrenheit the vent is fully opened to provide fresh intake air and fully closes at approximately 40 degree Fahrenheit to conserve energy and protect pipes. These vents are easily installed using screws or screw anchors or with retaining clips. Both are included with the vents. No mortar is required for installation.