Madco Machine has designed a patent pending lock that that will keep your trailer secure. Madlock is not just another universal trailer lock. To keep your trailer secure we are making a few models. 2 5/16" stamped coupler sizes are currently in production. 2" will be getting into production shortly. We are also currently designing locks for other applications as well. Need a lock for an application that we don't currently supply? Give us a shout!