An additional note on the covers is that you can still get bugs and small debris collecting on the interior screen of the vent opening. You can try stuffing foam around the base of the cover, but whether or not it stays put is another story. On the 3670 covers I installed, I used the hinged brackets for the standard covers to make opening for cleaning easier. The large one for the Fantastic Fan does not have hinged brackets available, but I believe the interior screen can be removed easily from inside the trailer. When leaving the rig unoccupied or stored during the warmer months, you can leave the standard vents open a bit to help relieve some of the heat build-up.