






🏠 Stay safe, stay savvy — CO protection that’s always on, even when the power’s off!
The FIRST ALERT CO400-3 is a 3-pack of battery-operated carbon monoxide detectors featuring advanced electrochemical sensors for precise CO detection. Each unit emits a loud 85-decibel alarm to alert you of dangerous CO levels, operates independently of home power, and includes user-friendly test/silence functions. Designed for easy placement on every home level and bedroom, these UL-listed alarms provide reliable, continuous protection with a 5-year sensor lifespan and low battery alerts, ensuring your family’s safety around the clock.











| Alarm | Audible, Visual |
| Brand | First Alert |
| Item Weight | 0.5 Pounds |
| Power Source | Battery Powered |
| Product Dimensions | 1.5"D x 5"W x 3.4"H |
| Style | Battery Powered |
S**N
Great Carbon Monoxide Detector – Easy to Install and Reliable!
I bought two of the First Alert Carbon Monoxide Detectors (model CO400), and I’m very happy with them. They were super easy to install — no outlet needed since they run on batteries. I just mounted them on the wall, and they were ready to go in minutes.I like that the battery operation means I can place them anywhere in my home without worrying about finding a plug. The alarm is loud enough to hear clearly, and the design is compact and simple.It gives me peace of mind knowing my family is protected. Overall, great value, easy setup, and reliable safety product. Highly recommend!
S**H
Awesome
Great product!!! Works very well
S**N
Peace of Mind
Fair price, easy to set up and look good on the wall. It’s given me peace of mind during these colder months.
D**K
Easy to install
Work great but was to replace two that stopped functioning and never game any sort of warning beep. Hopefully these do a better job.
R**Y
Safety 1st
Great Value, Great Service & Great Product! Highly recommend for your safety & of your Loved ones!
S**N
Easy install
Easy to install. Set up in minutes.
D**T
Worthwhile purchase!!!
First Alert is a company I trust. As a gift for a couple moving into a new home with gas appliances, we gave them this 2-pack of carbon monoxide detectors. It even includes the batteries. Makes me feel that this was a worthwhile purchase for their home safety.
P**Y
for home, for travel, for car (add to winter car bag in case stuck in blizzard). 9 volt included
I purchased two packs of the pack of 2. So far so good!? Tested fine. Hope it actually works, which is why I went with a name brand. This is not the place to skimp. The C0400 carbon monoxide detector comes with a 9 volt battery. I knew I needed to replace my existing detector (they dont last forever, and need to be replaced ever so often) and I did not want the plug in style. I wanted battery operated so I could place it wherever I wanted and not be limited to available outlets. I also bought a second pack as a gift. I prefer giving practical, functional gifts, especially stuff that people tend to not want to buy, such as smoke alarms, fire extinguishers, carbon monoxide detectors. If you travel, consider a battery operated detector such as this. Dont trust that a hotel room has you covered, or someone else's house. It is small and light weight enough that it should be the thing to pack (take out battery, store separately until in room). I will likely buy an additional pack. Right now I have one on the first floor, and one outside my second floor bedroom door. I think having one in the basement and another in actual bedroom or elsewhere (spread out) would be better. Watch for sales, but if need be just buy them at any cost so you have them. I am even thinking about adding one to my winter car kit. If ever stuck in a blizzard and had to stay in my car for any length of time, having a detector will help as CO2 levels can quickly rise if running car (or if a few people are simply breathing without the window open a crack) to keep warm. Tail pipes can easily clog especially if windy. So yeh, simple thing to stay safe and alive
Trustpilot
2 weeks ago
2 months ago