The product alerts you to dangerous carbon monoxide levels. This carbon monoxide detector operates on a dual-power system with battery backup for continuous monitoring, even in the event of a power outage. The backlit digital screen tells you, at a glance, what the carbon monoxide and power levels are. The monitor also features a convenient test and silence button and an end-of-life timer that lets you know when it is time to replace the unit.

Thankfully, I have not had it go off due to us not having carbon monoxide in the home, but we test it every week and it’s loud!!!. Diane. Terryville, CT. Wed Jan 01 2020

This plug-in electrochemical explosive gas and carbon monoxide alarm features a backlit digital display, this explosive gas, and CO detector plugs into any AC outlet with no additional mounting hardware needed.

It's an alarm -it seems to work -haven't had a chance to truly try it out -which is good -so that is all I have to say about that lol. Kimberly. Boston, MA. Tue Mar 10 2026

The 3-in-1 Explosive Gas & Carbon Monoxide Alarm from First Alert(R) warns against natural/methane, propane and carbon monoxide. The digital display makes for easy reading during an alarm or when any button is pressed. The alarm plugs into any standard outlet with no additional mounting necessary and comes with a line cord, which offers multiple placement options. The alarm also comes with a battery backup in the case of a power outage and utilizes an electrochemical carbon monoxide sensor for increased accuracy. Meets UL standards.

its an alarm -how excited can you actually get over it -lol??. Kimberly. Boston, MA. Tue Mar 10 2026

This dual-function alarm detects both smoke and carbon monoxide, with a clear digital display showing real-time gas concentration levels (PPM). When either gas is detected, the device emits a loud, continuous beep to ensure prompt alerts. Powered by 3 AA batteries (batteries not included — customers are required to supply their own due to national regulations). Designed with low power consumption for extended standby life, and features a low battery warning along with automatic sensor fault detection. A smart, reliable safety solution for any home or workspace.

Practical and needed, good value.. Victor. Cincinnati, OH. Sat Oct 17 2026

The First Alert SMI100 Battery-Operated Smoke Alarm is easy to install and features First Alert's Precision Detection advance sensing technology. The front access battery compartment makes for quick battery replacements and a low battery warning will advise when it's time to replace. Discourage unwanted removal of the battery or smoke alarm using the optional locking features. Use the convenient test/silence button on the front of the smoke alarm to check that it is operating properly and silence false alarms. An end-of-life warning will advise you when it’s time to replace because alarms don't last forever. Effortlessly install the CO400 Battery-Operated Carbon Monoxide Alarm throughout your home for reliable CO protection in minutes. Operation is simple. Test the CO alarm using the single test/silence button. The low battery warning will notify you when it's time to replace the alarm's battery, which is quick process due to the front access battery door, and an end-of-life warning will alert you when it's time to replace the alarm all together.

working good no problems easy installl. Jack. Prescott, MI. Sat Jul 25 2026

This First Alert carbon monoxide alarm features a 10-year built-in lithium battery for continuous monitoring during the life of the alarm, and uses an electrochemical carbon monoxide sensor and an 85-decibel alarm to alert you to CO threats. The advanced electrochemical CO sensor detects carbon monoxide leaks from multiple sources, such as faulty fuel-burning appliances, blocked chimneys, and generators running inside or too close to homes. Because CO evenly distributes itself, it's important to have a CO detector on every level and in every bedroom of your home. This easy-to-use alarm features a digital display that shows ambient temperature as well as peak CO levels. The detector's stylish design looks great on top of a dresser or table.

Love the product… Easy to setup…Test Alarm feature is also very helpful.. Vamsi. US. Sun May 14 2023