Product review (1 stars): Don't waste your money.
Bought 5 of these to measure room temperature and humidity in our pharmacy departments. The temperature works fine, but the humidity stays at 10% at 5 different locations basically 24 hours a day. I even put one in the refrigerator for 4 hours and when I pulled it out , wow! it was 10%
Sent manufacture and email inquiry with no response. Now I need to replace them all.  I'd look elsewhere if you want something that works.