Product review (5 stars): Excellent customer support
I bought the TP63 mainly to monitor our indoor humidity for various health related reasons. After a few days I got the feeling the humidity was reading quite low. I compared it to an older analog gauge (which I would not have expected to be accurate), the hygrometer on my new Aprilaire humidifier (which I would expect to be accurate), and after leaving it outside in the shade one nice day I compared with the current conditions posted by the local weather service. The TP63 seemed to be running about 8-10 percent low. I replied as such to the vendor in response to their "how do you like it" email and they provided lots of useful information about humidity and immediately sent another one for me to try.

In the meantime, I also did some research on line and found out how difficult it is to get accurate humidity readings, especially at low cost. I also found a cool way to test your hygrometer. Just search for "salt water test for humidity" and there are plenty of web sites and videos that describe it. After trying that, and comparing with the second TP63, I am convinced that it is accurate within 1 or 2 percent, which is well within reasonable expectations at this price point and more than sufficient for my needs.

Very satisfied with the product, and especially satisfied with the customer support.