The Master Lock 1479TAT features two 5/8 inch (16mm) class III/IV barbell receiver locks, keyed alike. The receiver lock includes the push to lock locking mechanism, easily used by pushing the lock body firmly onto the pin and removing the key. The weather tough seal and water tight cap provides additional protection from moisture and dirt. The limited lifetime provides peace of mind from a brand you can trust. Class III/IV, 10, 000 pound load rating.