With over 50 years experience in making life saving home safety products you can feel confident in the quality and dependability of BRK. With electrochemical carbon monoxide sensors the most accurate type of sensor for carbon monoxide detection the Carbon Monoxide Alarm with Battery Backup will provide comprehensive protection even during power outages. Product Information: Intelligent Sensing Featuring Intelligent Sensing Technology™ the BRK CO5120BN is able to reduce the amount of nuisance alarms such as cooking. Tamper Resistant Featuring a tamper resistant locking pin the BRK CO5120BN prevents removal of the battery making it perfect for apartments hotels or dorms. Battery Backup Featuring battery backup the BRK CO5120BN will keep you safe even during power outages. End of Life Signal The BRK CO5120BN has an audible end of life notice after 10 years when it s time to be replaced. Alarm Reset The BRK CO5120BN will automatically reset when the carbon monoxide gas clears. Interconnectable The BRK CO5120BN can be connected to up 18 compatible alarms 12 can be smoke alarms. The CO5120BN is also compatible with First Alert interconnectable alarms. Specifications: Power Source: Battery Hardwired Battery Requirements: 1 Lithium Battery Width: 5-3/4 Height: 5-9/16 Depth: 2-1/8 Voltage: 120V