Product review (2 stars): Bugs, dust and water can get in....get one with a damper.
The was the original on our RV. With no screen or damper, it allows dust and bugs in to the interior quite easily. In a tropical storm (or many other storms in FL) it can "rain sideways." And when it does, it rains into the vent and you will be cleaning up a large amount of water on the interior and taping it closed on the outside. Suggest you get one with a damper that can be closed when not in use or in inclement weather.