Air Vent Foundation Vents help remove moisture which can lead to rot, causing expensive damage and attract termites. They are offered in multiple styles such as a powered, automatic or manual foundation vent. A powered foundation vent is recommended for more hard to vent foundations and includes a small fan located in the housing that runs when the humidity levels increase. The automatic foundation vents fit most block openings and open and close when the temperature reaches a certain temperature. Manual foundation vents include a slider or accordion mechanism that has to be opened and closed manually by hand. Air Vent Foundation vents are offered in multiple different finishes to fit every need and help increase ventilation in any home.