I have a knock-off brand of Maxx Air style vent covers on all 3 vents on my ccurrent amper. No problems at all. Reason I had them installed on my new camper is because last Summer, hail knocked out both vents and the shower skylight. So we decided when we got our new camper last September, we'd get the covers. Figured it was better to have them beat up by hail (if it ever happened again), than have the vent covers beat out and then rain come in! So went with the cheap knock off brand. So if it ever gets beat up and broken by hail again... I'm not out that much money. I figure an expensive one will get destroyed in hail just as easy as a cheap one. And if they have to be replaced, the process is the same for both.
It is VERY nice to leave the roof vents (all 3 of them) open, even when it's raining, or even when driving on the road! So far, my cheap-o-vent is doing just fine! It appears to be nice and healthy! No signs of age or distress, and they survived their first winter, a couple near miss tornadoes, and lots and lots of high wind! This has been a REAL interesting weather year!