The First Alert long life battery smoke alarm features an extended long-life lithium battery that is warranted by the manufacture to ensure a decade's worth of protection. This effectively translates to ten years of constant and undisturbed coverage. Utilizing an Ionization Sensor, this alarm is especially effective in recognizing smoke brought on by flaming fires. This alarm comes equipped with a mute button that serves the dual purpose of quickly silencing your alarm as well as testing its function. First Alert's long life battery smoke alarm also features an EZ access battery door that removes the hassle and burden of collecting your alarm from the ceiling and replacing its batteries. This alarm carries a 10 years limited warranty and meets UL217 Standards.