The instructions for mine said it was "weather resistant", but I from looking at it, I did not think it looked like it should be mounted full time outside. I have a small solar panel that I connect to the battery when the trailer is in storage that uses one of these
12v connector, so I picked up one at an auto supply store, and put the repeater on top of the battery with Velcro - the box is pretty well protected as it is tucked under the "nosecone" of the trailer. Seems to work fine, and can easily be removed and put away when not needed.
Edit: It is nice to have it where you can easily view it during pit stops so you can see whether or not the LED pilot light is on ....
