With this door/window alarm, you can secure doors & windows effectively & cost-efficiently, without complicated installation work. The main unit with the magnetic switch is mounted directly on the door or window frame. If the protected door or window is opened without authorisation, the magnetic switch immediately sets off an alarm. You can open the door or window without setting off the alarm, by entering a 3-digit code number. This number can be set individually. When used as an entrance control, a gong or tune is sounded instead of the alarm signal.