The Thin Door/Window Contact is designed for use on doors windows and other objects that open and close. It communicates with the control panel using the 345 MHz frequency. When the magnet (which is mounted near the sensor) moves away from or closer to the door contact?s sensor signals are transmitted to the control panel. The door contact also has an external input that accepts connections from normally-closed (NC) dry contact devices. For added protection it is also equipped with a cover tamper.