The First Alert FG200 Smoke Alarm is a battery operated ionization smoke alarm to keep you and your loved ones safe! Ionization smoke sensors are generally more sensitive at detecting small particles, which tend to be produced in greater amounts by flaming fires. A beeping signal warns when the battery needs replacing and also has a test button to set your mind at ease that all is working order. A hinged cover makes for easy battery replacement. 9-volt battery and 3-year limited warranty are included. Meets ANSI/UL217 standard. Low battery signal mute Quiets low battery signal for up to 8 hours Electrochemical carbon monoxide sensor most accurate technology available for detecting carbon monoxide End of alarm life timer Alarm chirps when it is time to replace it 2 AA batteries included Loud 85db alarm 5-year limited warranty carbon monoxide alarms should be replaced every 5 years for maximum protection