Place the AlertMaster Audio Alarm Transmitter unit next to any audio alarm or timing devices in your home up to 80 feet away from base unit. Once the alerting device is triggered, this alarm device will send a wireless signal to a receiver to alert you. The AlertMaster Audio Alarm Transmitter works well with timers or fire, smoke and/or carbon monoxide detectors. Operates on a 9-Volt Battery (included). Covered under a 1-year manufacturer warranty.