I put a couple MaxxAir 2 covers on our greyhawk. One is over a manual vent the other is over a power one. The power one stops fine when it hits the vent cover. One thing to note, the black ones block out all the light. We originally purchased black to match the AC and other roof mounted items, but it made the bathroom and bedroom area too dark, so we went with the white (which lets a lot of light thru). Just something to be aware of.
2016 Greyhawk 31FK