Chinook RV

I got up on the roof of my Chinook to take a look around. Two questions:
1) What is the thingie in the left rear corner that spins around like a wind vane? 2) Any suggestions on how to replace the MaxxAir Vent Cover that is cracked open?

1) That is where the black / sewer tank vent is on my rig. I have seen some vent covers that are designed to pull odors out of the tank while the vehicle is in motion, I'm guessing that is what you have there.

2) These are widely available and cheap. The Maxxair cover is aftermarket and only there so you can open the actual fan vent lid while it is raining, and/or to reduce noise, you don't technically need it. It unbolts with the four exposed fasteners you can see in your picture.

Here is what you would need to replace it:

https://www.amazon.com/Maxxair-503-15-0 ... ive&sr=1-2

Thanks for the good info!