Single ionization sensing chamber
10-year sealed Lithium battery for continuous protection
Eliminates low battery chirps
Audible end-of-life signal
Full function test/silence button
LED indicator light confirms alarm is on and working
Wall or ceiling mount (hardware included)
Tamper-resistant design
85 dB alarm at 10 feet

No batteries required. 120 volt plug-in. With silence feature, samples the air and performs self-diagnostic tests approximately every second. A microchip inside the unit stores each reading, and remembers the levels of CO it has been exposed to over time. Controls are: test/silence button, green power light, yellow service light, red alarm light. Loud 85-decibel alarm, UL listed. 5 year limited warranty. 3.3" height x 4.75" width x 2" depth, 0.24 pounds.

The FIRST ALERT CO400 carbon monoxide alarm utilizes a electrochemical carbon monoxide sensor that lasts for up to 5 years to detect carbon monoxide. This carbon monoxide detector is battery powered, making it portable and easy-to-use anywhere, even in the event of a power outage. When carbon monoxide levels become elevated, a loud 85 dB alarm alerts you to the threat.

Voice Alarm -Announces the hazard type detected thereby helping to speed up the correct reaction to the hazard detected. Alarm announces "Fire!" when a smoke or fire hazard is detected and announces "Warning Carbon Monoxide" when a CO hazard is detected.
Combined Carbon Monoxide and Smoke Alarm - A single unit can be installed where previously, two were needed. Reduces installation time and helps to keep home decor attractive.
Test/Reset Button - Tests alarm circuitry and triggers the voice announcement.