I mounted them on each tire on one side of a two axle livestock trailer. The trailer was stolen with wheel chocks installed. Apparently they broke after a few kilometers. When we found the trailer, there were no locks and only the wheel arches were damaged. They can serve as a deterrent to an ambitious thief, but not to a thief who decides to steal a pendant. One might assume four locks would be more efficient, but I think the result would be the same. I would suggest finding alternative methods of protecting your vehicles and trailers.