Inside the shutter are 3 magnets faced in the key "CODE". These 3 magnets pull PUSH 3 small steel balls out of dimples and allows the shutter to turn.
In the key's head are 3 magnets facing theopposite SAME way for the code.
Edited for comment in post below.
In the key's head are 3 magnets facing the
Edited for comment in post below.