Our Smoke & Fire Detector uses a lithium battery that you won t have to change for 10 years! That s more protection than most other battery powered detectors! It has a loud 85 decibel alarm that responds immediately to smoke or fire, and an indicator light that flashes every 45 seconds so you ll know it s working properly. The special silencer button decreases sensitivity for 10 minutes for fewer nuisance alarms. Low battery signal beeps when battery needs replacement. UL approved. Lithium battery included.