The Kidde P4010ACS is an AC/DC powered, photoelectric smoke alarm that contains a 10-year, sealed battery backup and voice messaging system. The voice warning feature accompanies the 85dB tone during an alarm event, and helps reduce confusion with verbal announcements such as “Replace alarm” at end of alarm life, and “Hush mode activated” when a nuisance alarm is silenced. Kidde P4010 Series Alarms contain 10-year tamper proof batteries that eliminate the need for battery replacement, and ends worry over unauthorized removal. Users are further shielded from late night battery chirps by the unit’s Ambient Light Sensing feature, which establishes a day / night cycle and prevents alarm chirping in dark conditions.