Be alerted of danger immediately with this emergency transmitter. Simply attach this alerting device to a smoke alarm, carbon monoxide alarm or other audible alarm in your home via the hook and loop type fastener. The emergency transmitter detects the sound of an active alarm and transmits it to the KA300 Alarm monitor receiver. This transmitter can also be used with the WR300TX Weather Alert Transmitter. Measures approximately 2.55 x 1.57 x .69. Weighs approximately .088 pounds. CR2032 battery included.