Product review (4 stars): Everything was packed well - no damage but easy to unpack
I was looking for a CO2 meter and didn't want to spend an insane amount of money. This was the least expensive, decent looking one, so I purchased it.

The meter arrived quickly - 4 days or so from the order with standard shipping. Everything was packed well - no damage but easy to unpack.

I can't comment on accuracy since its my only meter, but the outdoor CO2 measurements are consistent with what internet research suggested they should be. I found that,the CO2 levels in my house start around 475 - 550 when I get home from work, raise up to 950 - 1200 by the time I go to bed if all windows and doors are closed. During the night the drop back down to 700 - 800 by the time I get up (I assume because I'm producing less CO2 when I sleep.

The reason I bought the meter was that I was waking up with less energy than before in my new house. After searching around the web a bit, I became interested in CO2 accumulation. Based on the readings I got, I started opening a window in my bedroom for just a few minutes before going to sleep. This drops the CO2 levels to good/normal and they never raise above normal while I sleep. I bought a new pillow for better neck support at the same time, so I'm not sure which is doing the trick, but I feel better in the morning than I did before - not perfect, but very noticeably better. If nothing else, it is very interesting to see how CO2 accumulates in your house throughout the day.

As other users have commented, the interface is not super easy to learn (- 1 star), but you really only have to set it up once (Plus an occasional outdoor calibration procedure). It takes 15 minutes to read through the instructions and get everything you need set. For an inexpensive meter, this would not deter me. I would buy again.