Wireless opening detector that reports the first signs of intrusion into a room through a broken door or window. It can be mounted on all types of doors, including metal-based doors. The device detects the opening of doors or windows using high-quality British-made reed switches that are acted upon by the magnetic field. The device consists of two modules? Detector and magnet. The set contains two magnets: the large magnet is installed at a distance of up to 2 cm and the small magnet is installed at a distance of up to 1 cm.