The union strongbolt 5 lever mortice deadlock visi 79mm has a radius inner forend for ease of installation they can be installed in the many uk mortices without the need for additional carpentry or spoiling the edge of the doorthe chamfered bolt design increases the performance of the lock under side load testing and also makes drilling attack more difficult anti pick and keyhole protection prevents forced entry by picking and the hardened steel pins provide resistance to attack from sawing