The Lifetone HL Bedside Fire Alarm and Clock is proven to be more effective at alerting and awakening at-risk individuals than standard fire alarms. A state of the art fire alarm and an attractive and easy to use alarm clock Listens for your existing T3 smoke alarms (the most common ones available) and then broadcasts its patented low frequency, 520Hz square wave sound pattern Ensures a life-saving environment for people with hearing loss, seniors, children, and heavy sleepers Features: Uses 520 Hz square-wave sound pattern - a lower frequency than traditional smoke alarms Hears your existing T3 smoke alarms. No new alarms are required. Alarm Signal at 85 dB of gain No installation or wiring required, only power outlet Battery backup lasts 7 days or more Provides emergency alarm signals in battery backup mode Comes with a water-resistant bed shaker Alerts to AC power loss and low or no battery Alerts to unplugged or defective bed shaker Functions as a standard alarm clock Two year limited warranty Dimensions: 8 1/2" L x 5" W x 4" H