Review on CZC AUTO 12V Two Sided Magnetic Towing Light Kit - Powerful 55lb Magnetic Strength for Trailer RV Boat Truck by Scott Channell

Magnets are strong. They didn't fly off the trailer at all and were moving at full wind power at 70-80 mph on the interstate. I've seen a few reviews of magnets not working, but it's probably something to do with the thin metal. The rails I attached them to were 1/4" (0.25") steel. If it's really thin steel, like 18ga (0.04") or even 16ga (0.06") they might not hold up. 11ga (.125) will probably hold. All I had to do was take the red/yellow plastic off of them and rearrange them, which wasn't difficult. This is a huge improvement over the spoiled, mouse-eaten ones. wiring harness on my trailer. After you're done with them, I suggest you take them down, pack them up, and store them in a shelter. Don't leave them outside, there's no reason to ruin them unless you want to leave them outside in a trailer.