Caddx Battery Door/Window Sensor with 150m Range 433MHz Wireless Transmitter in White Color RF-DC101-K4

A door/window sensor consists of two parts, one of which is placed on the moving part of the door or window, and the other on the fixed frame. In this way, when the two contacts move away, the sensor is automatically activated. It works with batteries and can be placed anywhere as it does not require a permanent connection to the electricity.