First Alert Smoke and Carbon Monoxide Alarm, Alarm: Voice, Photoelectric Sensor, Battery backup.First Alert Precision Detection advanced sensing technology reduces cooking nuisance alarms and delivers early warning.Voice & location alerts tell you what the danger is and its location.Battery backup provides continuous protection during power outages.Test/Silence button allows for efficient testing and temporarily silences alarm for up to 8 hours.Interconnects with most First Alert and BRK alarms so when one sounds, all compatible alarms sound to provide an early warning.