First alert 10 year lithium power smoke alarm p910b

The First Alert 10 Year Lithium Power Smoke Alarm P910B is a smoke alarm that features a built-in 10-year lithium battery that provides continuous power for the life of the detector. It has a photoelectric smoke sensor that is more sensitive than ionization at detecting large particles from a smoldering fire that doesn't have flames. It also has a patented smoke entry system that reduces false alarms.