The Kidde P4010ACSCO is an AC/DC powered, combination photoelectric smoke and carbon monoxide 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. Features: Photoelectric Sensing Technology; 10-Year Sealed Lithium Battery Backup; Voice Messaging System; Ambient Light Sensor; Smart Hush® Control; Flashing LED Status Ring allows easy identification of current state of alarm; Voice Notification: Verbally announces .Fire!. or .Warning! Carbon Monoxide!. to help distinguish between threats.; Easy to Install: Backup battery automatically activates when the unit is attached to the mounting bracket; Photoelectric Sensor: Smoke sensor contains advanced photoelectric sensor that may detect visible particles (associated with smoldering fires) sooner than ionization alarms.; Ambient Light Sensing: Establishes Day/Night cycle and delays chirping during the night until the next Day cycle begins.; Test / Hush® Button: Tests alarm circuitry and activates Hush® feature to temporarily silence nuisance alarms for up to 10 minutes. End of Unit Life chirps can also be silenced.; End of Unit Life Warning: Alerts user the alarm is in need of replacement.; 10-Year Limited Warranty - Warranty: 10 year limited