For 2017 and older Casitas with the Fan-tastic vent fan, this is a “mandatory” upgrade. The cover allowed us to run the fan in any weather. We could also leave the roof vent open while in storage for air flow. Installation was straightforward almost following the instruction sheet. The hardest part was not falling off the top of the camper! Instead of following the first part of the instructions and drilling 3/16″ holes for bolts, (there’s no access to put nuts on them), drill smaller 3/32″ holes and use the included screws (2 per bracket) and screw them into the plastic housing. One side is hinged and the other side had quick release pins to easily open the cover to clean.
We started with the smoke colored cover and changed the inside lid to clear. That combination brightened up the interior. After we moved to Miami, it let in too much sun! We swapped over to the translucent white cover and I think it looks a little better and keeps direct sunlight from beaming in through the roof.
The amazon links to the covers are here, just click on the picture. White: