product features：
The mechanical device with excellent durability has passed more than 400000 comprehensive action tests.
Pure mechanical code lock, no electrical wiring, no battery, simple installation.
12 buttons can be used to combine memory numbers, and more than 4000 memory numbers can be selected.
Slippage device: it can disable the attack and destruction from outside.
No matter whether it is locked or not, you can go out freely from the room without entering the memory number.
