QP Pro 2 Air Quality Monitor

Everything is great except...um, they aren't accurate.

You should buy 2 of these and run them side by side. If you are like me, you won't get the same TVOC or RH readings from your 2 units. Both units give me the same Temperature and PM 2.5, but any cheap device can measure those things. The CO2 readings are close enough. But the RH and TVOC are not. RH readings on one unit are off by 10% (as confirmed by 3 independent hygrometers), and the TVOC readings on one unit are 3 to 10 times higher than on the other (which is the difference between GOOD and DANGEROUS). Which unit is right? Maybe if I bought a 3rd one I could hazard a guess. In short, these devices are probably fine for determining whether TVOC is changing up or down over time, or whether it is higher in one room than another, but they are not well-calibrated and you can't take the actual numbers they produce seriously.

Finally a product that does exactly what it claims

Pleased with my product and even more with the customer service ! Thank you.

Great for monitoring room air

This is the only similarly-priced monitor I could find that measures both PM2.5 and tVOC. It's great for a stationary monitor, but having found it when searching for a portable monitor I'm disappointed that it's not suitable to carry around. That it has a battery to run unplugged is still nice, but not something I expect to use much. The only other problem so far is that I had to connect to WiFi and get a firmware update before I could set the date - I wanted to use it around people who don't want WiFi devices near them