Product review (4 stars): Excellent device, inexpensive price
I have had this CO2 meter for about a month. I have been using it to monitor c02 levels in a small greenhouse. It is very sensitive. When I enter the greenhouse the carbon dioxide from my breath causes the reading to start rising. Compared to other CO2 meters this item was only about 25% of the cost. The single negative for me is the alarm function. When the C02 level climbs above 1000 ppm, as it does several times a day in the greenhouse, an alarm begins to sound. Hitting the reset button temporarily turns off the alarm, but I have found no way to disable it for good. This makes sense if you are using it as an air quality meter, but I am not so it is an annoyance. I do like the min/max memory function. I would buy this again, and reccomend it.

Pro: Inexpensive, sensitive, min/max reading

Con: Haven't been able to turn off alarm