First Alert battery operated talking combination smoke alarm and carbon monoxide detector has a mute button to silence any nuisance alarms. Single button tests all alarm functions. Voice alarm is easy to program for alarm's location within the home (11 pre-programmed choices). Voice alarm also notifies which hazard is being sensed. Studies show that children respond best to voice. Photoelectric smoke sensor reduces nuisance alarms from cooking smoke or shower steam. Uses an electrochemical carbon monoxide sensor-the most accurate technology available. Easy access front loading batteries: no need to remove an alarm from the ceiling to change a battery. 7-year limited warranty. Meets UL standards. Meets code.