Wireless Magnetic trap BS-471 for doors and windows.
It is designed to detect when a door or a window is opened or closed. It can also accept input from an external magnetic contact (Normal Close). The detector is powered by battery. It consists of two items, the electronic device and the magnet.
It is used as add-on peripheral wireless device of the
Burgler Alarm System DIY BS-468/A/WL/KIT