Product review (4 stars): Good Value for the Money
The part that tells the humidity level is a bit iffy in lower humidities. My house got very dry last winter, and I bought these as well as a humidifier. After about 10 minutes of turning them on, three of the four synchronized enough that they were within 2 degrees and 5% humidity difference from one another. That's what the manufacturer states is the range they might vary at (if you need something more accurate, you also need something more powerful and thus more expensive). The fourth one, although it's temperature was within the 2 degrees, it's humidity reading was always 10% or more lower than the others. Now, we're talking less than 20% humidity max. Over time, I noticed as the house got less dry (from running my humidifier) that the 4th one now varied between 7 and 10%. I figured I had just got a fluke, and put it in a room I didn't care so much what the humidity was. Well, this summer as the humidity has increased to above 50%, I noticed that its humidity indicator had "caught up" with the others. So these are less accurate at lower humidities, although that is consistent with my understanding of how these things work.

I do wish they came with a light, maybe something like what watches have, where you push a button and the screen glows. That's definitely not a big deal; it's just that sometimes when I would wake in the night, I would want to check the temperature or humidity levels.

Overall, these were a good purchase.