Modern Keypad lock
Coded Door Lock: Mechanical and Electronic : Modern Keypad Lock
Quote from Article entitled Coded Door Lock: Mechanical and Electronic:
For reasons of safety, it is recommended to carry out transcoding of coded lock on a front door at lest once every month. This is easy and quick process, in the presence of the built-in secret mechanism and of understanding of his actions.
The full version of the article can be found here.