Simply attach the MaxxAir Roof Vent Cover to your standard 14" x 14" RV roof vent vertical flange and get rid of stale air, smoke, odors and excess heat while preventing rain, bugs and leaves from getting in. Easy-to-install Zero-Leak mounting system lets you avoid drilling holes into your roof's surface. Removable screen behind louvers keeps bugs and leaves out. Not recommended for use with fan vents.