I had the regular MaxxAir covers on my vents. I replaced them with the Fan-tastic Ultrabreeze covers to increase the air flow and they do move a lot more air. The problem is, if the rain is coming from the louver side, it will come into the RV. The louvers do not angle down like the MaxxAir II and MaxxAir covers do.
If I had it to do over, I would go with the MaxxAir Fan/Mate
Steve, Mary & Buddy our 2-year-old Chihuahua mix
1995 36' HR Endeavor, 460 w/Banks, 2005 PT Cruiser
Fulltimers originally from Michigan, hanging out in Oregon for a spell.