I took the unit outside in order calibrate it. It then read 408PPM, which is exactly what it should be, so I'm assuming the CO2 sensor is accurate.

But the relative humidity is a different story. I have three hygrometers in my mushroom grow tent. They all read within 3% of each other at 87-90% humidity. This unit consistently reads 75%, or roughly 15% low. While there is a way to calibrate the CO2 sensor, I don't see a way to calibrate the hygrometer. I'm disappointed in the inaccuracy.

We wanted a CO2 detector for the cold room at the brewery and the Inkbird was a great more affordable alternative. I turned on a CO2 line next to it to check the alarm which is why you see the high number in the picture. It’s not quite as loud as your average home smoke detector but you can hear it from outside the insulated room which has two AC units going. The battery life appears to be about one day so it’s best to keep it plugged.

Glad to have this safety alert now in case of a CO2 leak.

My 9 year old loves this metal detector. The battery last a long time and is accurate the sensor adjustment work good. I recommend it.

So far this driveway alarm system has been reliable and working perfectly. I have 2 sensors installed outside and the base monitor inside the house fairly close in proximity. The sensor are exposed to cold and rain and have been installed for about a month. I turn the sensor on in the evening and throughout the night to wake me when alerted. One sensor tells me if something is close to our driveway in the cul-de-sac and the other sensor will tell me if something crossed the driveway. We've had a few problems of car prowlers in the area recently. It's worked perfectly although I think the local deer like to stand in front of them at ngith and make them go off over and over again. The system can't tell the difference between animals, people, or vehicles. But at this price one would not expect that. So far I'm happy with what it does.

Bought this CO2 sensor for my house and this works great. The screen is bright and very easy to understand all the readings. When the CO2 level goes up, I would turn on my air purifier and I can see the reading goes down. This is really good if you want to monitor the air quality inside your house. It also has temperature and humidity sensor. The wifi feature is really nice addon.

I accidentally ordered two. They came charged. Did not require the 24 hour calibration cited in the manual. I put it by a window fan to calibrate for 10 minutes. Sequentially, they both settled at approx 405ppm CO2. I recently purchased another AQI meter from TempTop so I was able to compare pm2.5 to some extent.

I've only had these a couple days but I've closely monitored and corroborated the circumstances. All measurements between both units are effectively identical, no variance unaccounted for. The CO2 measurements proportionally increased based on quantity of occupants in my office, if the door was open/closed, central forced air ventilation (A/C system), and window fan. Most observed ranged have been between 400 and just over 1000, though intentionally breathing on it will exceed this.

The PM2.5 measurements correlate with the TempTop, though PM2.5 and PM10 jiggle up to 003 over the base reading, which is negligible. Because I purchased these to fill the CO2 gap the TempTop does not capture, I don't have much more to contribute in these readings yet.

The temperature and humidity are in line with all my other devices as well.

There was a review regarding them recalibrating on their own. This is an optional feature if you read the book, though I don't know why someone would want that to be recurring regularly.

I said I accidentally purchased two... I think I'll get more. Maybe one for me, but others as gifts. I think it's valuable to know the quality of air being respired, especially in places you spend the most time.

.....

Update:
I purchased a QuingPing monitor based on other reviews I read, largely because it esthetically enumerated the measurements I was most interested in, being Co2, PM, and VoC. This revealed that I absolutely needed to calibrate these units... I assumed when I started them and they hung at 500 for awhile, that was a calibration phase; Anyhow, after calibration they are coming congruent with the QuingPing. Even uncalibrated, bringing this unit to restaurants and my vehicle, etc still demonstrated increased Co2 and PM values, that even if the "floor" was high, was still valuable when taken relatively.

My opinion is that the Co2 alone is an excellent mechanism to measure ventilation in typical scenarios, and that can be used as an effective proxy for air quality generally. This assumes average room area, outdoor air quality, and no extraordinary sources of PM/VoCs like aerosols, flame (candles, gas appliances), or a operating workshop. For the budget minded, or entry level gifter, the Co2 only monitor would be good.

The construction of these are solid, even rugged, and the battery life has been at least adequate for my exploration. I appreciate the USB-C ecosystem. The color added to the screen, though it is static and never changing, makes it passable.

I'm probably going to move to QuingPing primarily, and use these as indicators suggested above (maybe in my car and/or kitchen). The QuingPing, while almost twice the cost, is quite featureful. It includes Wifi connectivity, with onboard and cloud telemetry logging, a nice touch screen and interface, is even more esthetic, and common home automation platform integration, etc. I'll probably settle for two QuingPing units, one in the bedroom and the other in my office. I'm still evaluating the accuracy before committing to a second unit, but it's looking promising.

Very nice and active

 My wife has been having headaches recently over the past few months and I decided to see if elevated Co2 can be the cause. Well, I was surprised to see the high levels of CO2 build up in our house. Having a good quality monitor like MOES WIFI Air Quality Monitor CO2 Detector with temp is very useful!
I like that this monitor is able to switch from C to F because I use F temperature here in the USA. This also comes with a rechargeable lithium battery with a capacity of 2400 mAh which makes this great for when I go camping with my propane heater.
Carbon dioxide, or CO2, is a harmless gas in the atmosphere, but if its levels rise inside a home, it can cause health problems for the people who live there. People and animals exhale CO2 as a natural function of respiration, so CO2 levels can rise if a home is overcrowded and has insufficient air exchange with the outside. Soil capping is a process that can occur in houses built on old farm sites when damp weather causes the soil to expand and release gases into the home, including natural amounts of CO2. Inadequate air conditioning systems can also contribute to elevated CO2 levels. Another source of increased CO2 is the use of fossil fuels in the home--so it is very important to have the tools to monitor your situation and warn you if something is wrong.
Attached are some photos to have a closer look at device. This is USBC which is awesome! The quality of screen is bright and very easy to read in day or night time situations.