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. This alarm uses breakthrough technology to offer a fast response to real fires, as well as protect you from carbon monoxide and dramatically reduce the chance of nuisance alarms. The Intelligent sensor technology combines the detection capabilities of a photoelectric smoke sensor with that of an electrochemical sensor, which is used to detect CO. Since carbon monoxide is present in all fires, having both detection chambers work together in one alarm is a breakthrough in the fire safety industry. When either sensor notices a potential hazard, it will communicate with the other. Depending on what is detected, the alarm will adjust its smoke sensitivity in order to better discriminate between a real hazard and a false one. This constant communication enhances the alarm’s overall performance in all fires, and significantly reduces the potential for a nuisance alarm. 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.