Air Vent® RABL Heavy-Duty Automatic Foundation Vent, Black, 50"Helps in removing moisture that can lead to damp rot and eventually costly damage, as well as attract termites. Automatic Foundation Vent take the worry out of remembering to open and close vents as the weather changes, so the home can be protected from decay. The vent has a Bi metal coil to open and close automatically without electricity. When the temperature reaches 70F the vent is fully opened to provide fresh intake air, and fully closes at