The Dometic Ultra Breeze Vent Cover is perfect for protecting your Dometic Fan-Tastic Vent without compromising on air flow. Not only does it allow you to keep your vents open in the rain, but the exclusive patent pending airfoil technology allows for up 75 Percent more airflow than competing products. The Ultra Breeze has been field tested to provide superior protection for your vents, while allowing between 95 to 100 Percent airflow.