Product review (5 stars): Definitely worth the purchase price!
Very pleased with these. I bought several, to keep in each case for every acoustic guitar in my collection..  Initially I kept them all together in one room with I higher end humidity meter to compare any variations between them for the first week after receiving them. It was reassuring to note that all of them consistently remained within 1 degree of each other, as well as the higher-priced humidity meter I was using as the standard! Living in the U.S., my only "complaint," which really is a non-issue, is that the temperatures are given in Celsius only. (I figure I should learn the Celsius equivalents anyway, since most other countries use that system!)