This smart door lock successfully saves the replacement cost when the door lock is damaged. Only the lock itself needs to be replaced without any electronic wiring and any changes on the door. It is very suitable for some ancient buildings that do not allow too many changes. It is also suitable for small hotels and small offices to solve access control problems. The installation process is also very simple. The installation can be completed without professional guidance. It is also simple and easy to use. The length of the lock can also be adjusted, and locks can be selected for different doors.