This model fits doors: 1-3/8" to 1-1/2" (35 to 38mm) Keyless Security SIMPLEX 900 series auxiliary pushbutton locks from ILCO UNICAN are designed for easy installation in addition to, or as replacement for existing locks. Deadbolt, and Spring latch models available. Simplex 900 series are fully mechanical - not affected by power failures. Mechanical pushbutton access controls provide a high level of security and eliminate the key control problems associated with the traditional metal key. These locks accept a private code (up to 5 digits pressed individually or in unison). You set your own code when the lock is installed. Simply press in the correct code to gain access. No keys to carry, lose or replace. Give the code only to the people who need access. Change the code yourself as often as needed in seconds without removing the lock from the door. This simple code change procedure eliminates the cost of rekeying doors due to lost, stolen or misplaced keys.