The EcoVent by Broan is the only exit vent to feature the patented floating ball check valve. This award-winning innovation improves air flow efficiency, reduces heating costs and provides an airtight thermal seal that prevents condensation in ducts while eliminating backdrafts to keep homes quiet and secure even on the windiest days. With EcoVent, animals can’t get in and heated or cooled air won’t get out. It is an attractive, easy way for homeowners to enjoy a more comfortable, secure and energy efficient home.