Product review (4 stars): Works as stated but not that useful as a lab instrument
It works, and humidity accuracy is as stated. About +/- 4% for mine (when I compared it to a $200 Exactech meter). HOWEVER, one thing to be aware of is that its lowest reading is 20% (mine actually goes down to 18%). So you can't use it to, say, check the humidity in a desiccator with a drying agent inside (which is what I wanted) as the humidity is usually more like 1% or less. Now this lower limit is stated right on this page so I can't fault them for false advertising, and that's not why I gave it only 4 stars. (FYI: yes I am very bad at reading the fine print.) Mostly gave it 4 stars because the thermometer accuracy on mine is not that good. It was saying 75 when the house is 69. Also it take a very long time to equilibrate -- tens of minutes in going from the desiccator to outdoors and back. My more expensive meter gets to the right reading within seconds.