pretty much a breeze to install took about 20-30 minutes per unit to drill and place on top of rig.
does limit the full open travel height of normal vents but not enought to hinder ventilation.
in the windy west, New Mexico works good for keeping vents from being blown around by the 30-50 mph gust.
Can't say about keeping the rain out haven't traveled to a state yet that gets rain.
Overall easy to install and has a lower profile than max air vents which normally reach the height of the ac units. 4 stars

Great service. Vender sent in 2 shipments in order to get them to me at the same time, as he had one and had to dropship the other. He did not charge me for the seperate shipment. The order was in perfect condition and very easy to install. I will use this vender whenever I can thanks. 5 stars

AERODYNAMIC VENT COVER. EASY INSTALLATION. OPENS LARGE FOR CLEANING. GREAT AMAZON PRICE AND FREE SHIPPING. 5 stars

Purchased a roof fan air vent by Camco. My husband was thrilled with the ease of securing it, the side air flow along with the rear. This product worked with Fantastic Fan which we were told would not. It is also $60 less than the competitor plus FREE SHIPPING! Thank you camco and Amazon 5 stars