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The First Alert CO400 carbon monoxide alarm uses an electrochemical sensor the most accurate technology available. The permanent sensor lasts up to 5 years. It is powered by a 9V replaceable battery giving you peace of mind even during power outages. The test/silence button silences the alarm and allows you to test its functionality. The unit monitors and re alarms if carbon monoxide level persist sounding a loud 85 decibel horn. No installation is required and the attractive design allows the unit to be placed anywhere you need it. It includes an optional wall mount with no outlet required. An audible and visual battery signal alerts you to replace the battery. Pull down action chart has convenient guide on what to do if an alarm sounds. 5 year limited warranty. Ul listed.
Amazon.com
Carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until its too late. Since symptoms of CO poisoning are like the flu, you might not even know you're in danger at first. That's why a carbon monoxide alarm is an excellent way to protect your family. It can detect the CO you can't see, smell or taste in the air. The First Alert CO400 carbon monoxide alarm uses an electrochemical carbon monoxide sensor-the most accurate technology available. The permanent sensor lasts up to five years. It is powered by on 9V replaceable battery giving you peace of mind even during power outages. The test/silence button both silences the alarm and allows you to test its functionality. The unit monitors and re-alarms if carbon monoxide levels persist sounding a loud 85-decibel horn. No installation is required and the attractive design allows the unit to be placed anywhere you need it. It includes an optional wall mount with no outlet required. An audible and visual low battery signal alerts you to replace the battery. Pull down action chart has convenient guide on what to do if an alarm sounds. 5 year limited warranty. UL listed. --Bree Norlander
Jennifer Hagerty
2025-08-21 13:04:36
This First Alert CO400 is a reliable and affordable way to protect your home from the silent killer, carbon monoxide. The compact design makes it easy to install in any room, and the battery-operated feature eliminates the need for hardwiring.The loud, clear alarm is easy to hear, and the digital display provides real-time CO readings. It’s reassuring to know that this device is constantly monitoring the air quality in my home.While it’s a simple device, it does its job effectively. Highly recommended for anyone looking for a basic but reliable CO detector.
Gabe Kasak
2025-07-09 15:17:34
This CO2 monitor is super easy to setup, affordable, and a reliable brand. Overall, it is a product that is super easy and functional to use. It has a solid alarm volume and gives me peace of mind for my garage space where I am regularly pumping my ventless natural gas heater.
Paul C
2025-06-17 15:41:21
This is the second purchase, meets all industries standards, quick install, open, tested and mounted in 5 minutes. Good to go!
melanie K
2025-05-26 17:13:59
I just had a maintenance inspection of my AC. It includes plumbing and electrical. The tech told me I should have a carbon monoxide detetector even though my house is all electric. He told me to put one by the garage door that leads into the house because of parked cars in the garage. I never really thought about that. Wether it's really needed or not this was cheap enough to purchase.The only thing id say negative is that I had to get a knife to pry open the battery compartment. It did not open as easily as it says. I just hoped I didnt break it but it finally came open.As far as I know it works as intended. I hit the test button and it's pretty loud.
Precise Disarray
2025-05-18 13:27:01
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
L Smith
2025-04-26 12:54:51
Best brand. I only use this brand. They function well and have great sound quality!
Cindy
2025-04-04 21:48:16
I ordered 2 after my hard wired detector quit functioning. I installed one near my garage and it picked up on some very faint gas that was being discharged from our golf cart batteries. Vey easy to install and comes with the battery.
Thomas Gracey
2025-03-13 20:01:13
Good inexpensive necessity.
roger skinner
2025-03-06 10:45:52
This unit is very similar to the one we had for over 15 years. CO2 is a danger & we now feel safe again with the new alarm in place. The unit is just a simple plug in, but we did have to read up on where to put it. Placing it correctly is important so study up & get it right.
Riza Gee Why
2025-02-14 17:04:08
Haven’t used it yet, but for the price it’s a no brainer. Carbon monoxide is a life threatening hazard and buying one or 2 of these carbon monoxide detectors is an essential for any household. I like that this is battery operated and can be placed anywhere.
JIW
2025-01-01 16:36:30
Works well and worth the $$$
Chuck
2024-12-26 12:42:12
Quickly mounted to the wall and put batteries in. Tested. Made beep noises that split eardrums. Due to the battery nature of it it can mount anywhere close to the ground to detect CO quickly.I wont truly know if it works, and I hope I never need to, but appears solid.
Francois Desrochers
2024-11-13 15:34:45
Nice shape. Works fine. Not bulky
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