This listing is for 120 units of 2GIG-DW10-345 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.