This fits nicely on our travel trailer power jack. We purchased it to stop the sun fading the black jack. Although we purchased and started using this a couple months ago, after days of heavy rain here recently we thought it would be prudent to check under it today. Yes, it is not waterproof BUT it was only damp under there and all the electronics still worked so we were happy. Let's face it, the manufacturers make the jacks to be weatherproof so a bit of water/damp should not hurt them. I do like another reviewer's idea of putting a plastic bag on first and then putting this cover on top though. A great idea!