First Alert P910E  10-Year Maximum Protection Photoelectric Smoke and Fire Detector with Escape Light, White Photoelectric Smoke Alarm Nuisance-resistant Technology In New Sleek Design 3v Sealed Lithium Power Sealed Battery Power Led & Alarm Indicator Mute/silence Button Complies with all current 10-year legislation in states/cities where required No Battery Changes for the Life of the Alarm; 3V Lithium Power Cell Included Includes an escape light to illuminate your path to safety Patented smoke entry system allows for a direct path to the photoelectric smoke sensor Nuisance free photoelectric technology reduces false alarms that result from cooking and shower steam