The comfort of having no need to use a key for opening or locking your door; the safety of not losing the key of your security door and no fear of having somebody stealing it from you or unlawfully duplicating it. Battery or mains (with rechargeable batteries) supplied. The lock works by entering a 4 to 8 digital code. You can store up to 128 codes From the inside the door can be opened by simply pressing a key. You can change the code numberless times and also entering an extra service code that you can delete if necessary. In case of malfunction, the electronics can be cut off, allowing to open and lock the door manually, by operating the cylinder of the lock.