Carbon Monoxide Detector 3 Pack CO Alarm Detector Voice Notification, LCD Digital Display, Battery Operated for House, Bedroom, Living Room, Garage, Hotel, Office (AAA Batteries NOT Included)

I tested these units by capturing some car exhaust in a large ziploc bag and then putting all the detectors all into the bag along with a professional, calibrated meter. They all registered within 10 ppm of each other and the calibrated meter and they all went off within a matter of a just a few minutes with a CO level of 200+ ppm. I tested an X-Sense unit next to these and the X-Sense unit didn't even go off after 20 minutes and did not even flash its LED.

Easy to install and gave us peace of mind. My wife's friend and her spouse almost died due to carbon poising. Thank God they are safe, however, since our heater is an older model, my wife thought it would be best that we install these monitors throughout our home. My wife is happy and that's all that matters to me.

They were easy to set and install. However, one did not work. It would not set at zero and kept going off the minute I put in batteries.

I bought these about 10 days ago thinking it was probably a good idea. Last night around bedtime my daughter noticed the one I installed was going off and the levels were over 400ppm! We put batteries in the other two to make sure it wasn’t malfunctioning and sure enough they all read around 400ppm. We were able to evacuate, air out the house and figure out the problem and I slept with one right next to our bed just to make sure. These are definitely worth the roughly $10/piece! We are really happy that we paid a little extra to get the ones that showed the levels and not just an alarm.

I'm not sure exactly how accurate they are, but I held it in front of a car exhaust and it certainly went off! Great value, I was able to put one on each floor of the house.

So my town or state forced us to get these type of devices in 2020. I smelled a rat that First Alert or whoever forced this to happen for their benefit but I figured, hey, it might be a good thing.I found this inexpensive no-name brand, bought some rechargeable batteries and decided to give it a try.Installation (for me) was easy because I bought this thick double sided tape stuff. I literally stuck these items to three walls.The thing is I never tested them. I've seen various people ask how to do that and I'm amazed nobody came up with the easiest way. If you have a garage -- turn your car on with the door close and leave this thing near the back of your car. I just did this after a year and thing went off in 20 seconds. Works.But the REASON I tested one (and the reason for a low rating) is that one of them went off and, well, never quite recovered. It was located by my kitchen stove despite nothing odd happening in the kitchen. To verify this I took the other sensors down and they had no problem.Apparently to 'reset' this device you pull the batteries out and put them back in. But it seems to have a memory and the first times I did this the same reading of 60 returned. (It's supposed to be '0'.) So I left it without batteries overnight and that seemed to reset it better. It didn't go back to zero but it did show a different number.I know enough about electronics to know that this device needs what's known as a 'hard reset'. It would force the device 'back to factory'. I'm of the opinion it utterly lacks one -- which means -- this is a device just waiting to break.If you read other reviews -- this seems to be the major complaint. One just FAILS and that's that. I took the one that failed and gave it the garage test. It did not trigger the alarm but the 60 number shot up to 114. So it's kinda working.I tried vacuuming all the holes in case dust has compromised the unit. Didn't fix it.It's only now that I notice no mention of warranty, no easy way to contact support. If someone who still possess the instructions to this unit can see if there's a way to HARD RESET the device, please answer my question in the product QUESTIONS area.Until I receive an answer on if this is fixable I'd not only NOT RECOMMEND but tell Amazon to pull this device as too unreliable to be sold.

This detector is awesome. They work as expected to. I tested one out with the car exhaust outside. Immediate results. Easy to set up. I feel better with them in my home.

Easy to setup and install however one did not work right out of the box. After installing the batteries and waiting for it to calibrate, the ppm level went directly to 51. After about 30-45 mintues the alarm started going off. I pulled the other two out of the box and inserted their batteries. They both read 0 ppm. Took them all outside for 20 minutes and no change. I'm assuming the 51ppm is defective and sending it back. The return process was easy and am awaiting my new sensors. I'm going to test the two "good" ones with auto exhaust to make sure they do register CO.