I read alot of reviews and this one was discounted and the right size for my rooftop. One review I read made so much sense to me… use flex seal spray on every hole and connections. Then spray with truck bed liner. So why was this critical? Not only does it add layers of protection and seals the unit so no rust, but also the bed liner gives it a slightly rough surface. If you’ve had roof racks of any sort, they seem to always whistle. People do strange things to break up the wind. That review and doing this was absolute genius! I went on my first ride just now and not even a clue something was up there! Excellent job!