Tri-Lok plug locks are available with either the 7-pin Ace cylinder or the Medeco high security cylinder with U.L approval. When a cylinder key is used the safety plug can be easily removed. This allows the regular doorlock release key to be inserted through the opening and the release of the shaftway door interlock. The safety plug helps to keep all unauthorized persons from using screw drivers, sticks, or bent wires to open the elevator shaftway doors when the elevator is not at a landing. Its main objective, when properly installed, is to aid in the removal of passengers, especially the handicapped, trapped in stalled elevators during a breakdown or power failure. It is also helpful to the elevator service and repair mechanics in the performance of their work. Specified by architects and engineers the world over for elevator door applications where safety, access, and security are important. Tri-Loks have been installed around the world in apartment houses, office buildings, hospitals, prisons, colleges and universities.