Carbon Monoxide Detectors, Portable CO Detector with Audible & Visual Alarm, 2.4-in Backlit Screen 0-1000PPM Travel CO Gas Meter for Home, Industrial and Outdoor (includes Battery x3)

This unit appears to work just fine. It was used to adjust the burn mixture for my tankless water heater as it was having issues staying lit and providing hot water. The tankless has settings for altitude (I'm at 7200ft) but some fine tuning needed to be done. This meter did the trick with the mixture adjusted according to the manual specs. All is well now.

Fast shipping. Easy to use. Will be very useful in my hvac business

I use it to check the CO level in my classic cars and it does it's job

The unit works as described. When I first set it up to use, I got no readings or feedback. I was uncomfortable with that not having any experience with CO dectors. I purposely struck a few matches and candles and checked the unit again and got some readings. I checked my range top again at various flame levels and after a short time (not fast as before) got some positive readings along with the audible tone up near the vent hood. Now I have my technique and my confidence in the meter. As it turns out, my gas burning equipment is within specifications. After some more research I have found that this type sensor probably should be replaced about every 5 years. Or more practical, throw it away and get a new one at that point. I will consider the need of this meter later, which is more sensitive, than the wall mounted smoke detection/CO units. CO is nothing to ignore and should be taken seriously.

Nicely price at tool check for carbon monoxide

The media could not be loaded. Bought this because we heat with a wood burning stove and wanted to check for co. We have alarms, but they are only set to go off for dangerous levels. When I got the product I checked around the stove and got a reading of zero. All good. I checked again after opening the stove to reload. A bit of smoke always escapes into the room at that time. Still read zero. Now I was getting suspicious, especially since the instructions say that standard living areas will have up to 9 ppm. This meter is supposed to read down to 1 ppm. Surely it should read something! I went to the closed garage and started my car. I went the rear of the vehicle and sampled the air at eye level above the exhaust...zero. So then I placed the device on a bucket near (not directly in) the exhaust and left the garage. I let the car run about 5 minutes. When I reentered the garage the device still read zero, even though I almost immediately started getting a headache. I turned off the car, opened the door, and ended the test. I may have just gotten a lemon, but clearly the device did not work. I am looking into returning it.

This device proves my work place is hazardous. Maybe changes will occur.

I originally gave this one star and wrote a very bad review (see below) based on the fact that after receiving this, I couldn't get it to register anything but '0', even after holding it in multiple car exhaust streams for minutes at a time.I started an Amazon return and picked up the package to take it to the return dropoff today and decided to power it up one more time. Lo and behold, it showed a '6' for a brief moment before returning to '0'. I hadn't seen it show any numbers at all previously.So, on a lark, I started one of my cars and walked toward the rear of the car, intending to hold this in the exhaust stream again to see if it would do anything different. I didn't even have to bend down. As I reached the back, the numbers started to creep up into the 20s.It works! (It works?)So I guess I'm going to keep it for the moment and I've increased my rating to three starts. However, I do not have a ton of confidence. Why on day one was I unable to get it to read anything at all, even by basically sticking it into the exhaust pipes of multiple running cars and holding it next to multiple household pilot lights?So... These apparently can and do work at times. Will it work for you? And will it work when you need it? I have no idea. Amended to three stars, albeit with some reservations.ORIGINAL REVIEW:Booted this up with the included batteries after reading through manual. It starts. It looks official and functional and it beeps.And it shows 0 ppm carbon monoxide.So I light a candle. Nothing. Hold it near water heater. Nothing. I go outside, start my car, and hold it in the stream of car exhaust, about a centimeter away from the exhaust pipe, for over a minute.0 ppm carbon monoxide.Now, given that people commit suicide by carbon monoxide poisoning this way, I'm pretty sure the reading in the exhaust stream should not be 0.In any case, I have been unable to get this thing to read anything but 0 ppm CO. I have read and re-read the manual multiple times.As far as I can tell, this device does nothing. Returning.