Air quality measurement is a very popular subject in electronics nowadays, and CO2 meters are one of the more hot topics in the DIY and maker’s scene, judged by the number of CO2 projects that are offered to Elektor for publication. But there are also affordable, commercially available CO2 meters in a nice enclosure, with a color graphic LCD. We were wondering what’s inside and if these devices or their components can be used for own developments. One way to find out: buy one, open it and do some reverse-engineering!