The kit consists of a sensor consisting of two parts from install in a door/window: Door opening detection. If the sensor main is mounted in correspondence of a door/window and the relative magnetic mini-sensor is mounted in correspondence with the door or the jamb, the opening/closing of the door itself can be monitored. The sensor rectangular with magnet can be installed on any door/window that you are interested in monitoring. When the door is closed, the two sensors must stand about half a centimeter apart. It is important that the magnet is brought close to the rectangular sensor in correspondence with the symbol of magnet drawn on the sensor.