KKnoon9 in 1 BT Air Quality Monitor CO2 Meter Carbon Dioxide Detector Time/Date CO2 TVOC HCHO PM2.5 PM1.0 PM10 Temperature Humidity Detection Support APP Control with Alarm Function for Home

The media could not be loaded. Unfortunately, the market is flooded with fake CO2 meters, and the KKnoon 9-1 is is no exception. When measuring CO2 levels, this device shows readings between 400 and 440 ppm (which is fresh air), while a reputable device displays 870 to 923 ppm and a true reading.Moreover, when you place a bottle of nail polish remover next to it, the CO2 value skyrockets off the scale. In the video the Kknoon is on the left, and the Co2 reading the top right corner. This suggests that the device doesn't actually detect CO2 but creates a reading based on other factors.For a visual comparison, see the video with the KKnoon device on the left. Avoid this product if you need accurate CO2 measurements, and always seek a device that uses an NDIR sensor.

Bought this as my Dad's been coughing a lot, and my asthmatic neighbour says he can feel the air is bad. Place needs a deep clean. Dusty tumbleweeds in the corners. So well dirty. I was hoping to get an objective measure I could identify problem rooms and make targeted improvements etc. BUT apparently everything is green 🤔

I bought two of these as I am curious about the quality of air in our home and wanted to measure two places simultaneously.Came promptly, we packaged and the units came charged. Good start.I turned them on, all functions appeared ok no problems. I downloaded the app, which unfortunately is not Google Play registered. I scanned the install file before installing with AVG and Malware bytes, all appears fine but you may want to do you own scan should you purchase for piece of mind.Units settle after 10 minutes. Obviously there is no way to calibrate or test that the units are working as intended. The readings appear to be reliable and they do fluctuate as you might expect if one breathes on the device. All readings seem "sensible" and both units side by side have consistent readings. All good so far. The display is bright and all of the readings are legible. You can easily connect the devices to the app via Bluetooth, it takes some fiddling but nothing too taxing.Now for the cons. Firstly, setting the date on the device can be very fiddly. It involves opening the app and then switching on BT, once you know how to do it no probs. The one massive issue is the low battery life. The description says 7 hours, unfortunately I think <5 is probably more realistic. It will need to be permanently plugged in for you to have the benefit of 12 hour read, not certain it is safe to do this.Summary, product seems to measure "accurately" and consistently when comparing the two devices. The item is small and can be placed on a shelf easily to measure air quality on battery for around 3-4 hours. The problems are the low battery life, the usb port is on top of the device rather than the back or the side. The app is not Play registered and can be a little fiddly until you know how to work the unit and app together.If you are serious go with a known brand for quality and consistency, if you want to do it on the cheap you could think about purchasing this device. It depends a lot on what you specific criteria are.

The battery will only last around 4-5 hours. This would be OK as could leave plugged in to power supply. However, USB-C charging port is on top of the device, with cable exiting upwards, unsightly and awkward for continuous powering.Nice looking unit, with clear vibrant display.Figures seem inaccurate and low compared to other units. Really, just a low cost novelty, you pays your money and takes your choice.

Calibrated against multiple different monitors, this one always reads CO2 400-420ppm no matter what the real ppm is (tested with real ppm range 500-1000).

Charged the item overnight but battery only shows two bars which lasted about three hours before running out. Returned to Amazon.