First Alert Digital Display Carbon Monoxide Alarm Battery-operated carbon monoxide alarm with backlit digital display. Uses an electrochemical carbon monoxide sensor, the most accurate CO detection technology available, to detect the CO you can't see, smell, or taste in the air. An easy-to-read backlit digital display allows a quick view current and peak CO levels. Powered by two replaceable AA batteries, offering peace of mind even during power outages. Battery life varies according to use and application. An EZ access battery door allows you to change out batteries without having to dismount the alarm. An 85-decibel horn sounds if carbon monoxide levels are too high, and a test/silence button silences the alarm and allows you to test its functionality. No installation or outlet is required, and an optional wall mount is included. Type Battery Operated, Voltage 3V, Battery Life Varies According To Battery Life, Sensor Type Electrochemical, Dimensions 5 In. W. x 1-1/2 In. H. x 3-2/5 In. L., Battery Back-Up Battery Only, Alarm Type Carbon Monoxide, Decibel Level 85dB, Battery Type AA Battery, Batteries Included Yes, Color White, UL Listed Yes, Warranty 7-Year Limited, Pkg Qty 1, Package Type Clamshell