When I leave my TT unattended at campgrounds, I install a lock that goes into the ball opening of the coupler, I lock the couple down, and I always have a locking pin in my hitch so that someone can't steal my insert/ball. Please remember that these things will only keep an honest person honest. A determined thief can get rid of those locks in minutes. With my battery powered angle grinder, I could remove all of them in under 30 seconds. I still use them to prevent crimes of opportunity.