The Trailer Guardian ($51) locks a trailer to a tow vehicle to help prevent accidental decoupling, it installs in seconds with a universal application (featuring 1/8-in. height adjustments) that fits all ball-and-coupler combinations. The Trailer Guardian also accepts a lock in one of the spring-pin holes to further secure the trailer to the vehicle. DuraSafe Inc, 865-544-5615. www.durasafelocks.com