Cheap but functional CO2 monitoring and logging device
It is cheapest option out there.
Compared two of these. Claimed accuracy is 7%. One was showing 800ppm while other one showed 900ppm. Could be within claimed 7%, if actual value was 850ppm.. could be not.
Finding software for data logging was very hard!
There were no download links provided in manuals and installing software was challenging as well (you have to rename .eye extension to .exe).
Look for "zyaura" website and find software download there!
Software itself has very very strange UI (somewhat funny).
If you are not looking for data logging but just plain CO2 value display, then look no further - this device is cheapest one out there AND!!! it uses laser technology instead of chemical sensor (so should be durable and more accurate over lifespan).