Security: This mortise lock is a high security internal door lock, there is a bolt on the top and a locking tab underneath. It has both a 2 lever locking system as well as a striker entirelyclosed to prevent burglars from tampering with the door lock. . THE LOCK BODY CAN BE ADJUSTED TO THE LEFT AND RIGHT: the locks are reversible and can therefore be used on either side of the door (left and right doors). Please refer to the 5th picture for the specific adjustment method. WIDELY USED: Tube frame lock for use with profile doors, tube frame doors, glass doors, plastic doors, aluminum doors or steel doors | can be turned, DIN can beused right/left. High quality mortise locks for residential or commercial use EASY INSTALLATION: Installation is quick and easy, and all mounting screws are included. Mortise lock easily slides into existing door pocket to repair a broken lock.