The First Alert Battery Operated Smoke and Carbon Monoxide Alarm SCO7CN is a talking combination alert system that tells you what part of the home is in danger and whether it is from a fire or poisonous odorless gas. Alarm is equipped with a mute button to silence any nuisance alarms and also tests alarm functions. Voice alarm is easily programmed for alarm's location within the home (11 pre-programmed choices). Voice alert on this First Alert carbon monoxide alarm notifies which hazard is being sensed–“Warning, evacuate! Smoke in Kitchen!” Photoelectric smoke sensor reduces nuisance alarms from cooking smoke or shower steam. This combination smoke and carbon monoxide alarm utilizes an electrochemical gas sensor for increased accuracy. Easy access battery drawer means no need to remove alarm from ceiling to change battery. The First Alert Battery Operated Smoke and Carbon Monoxide Alarm SCO7CN meets UL standards and includes 7-year limited warranty.