I get mine from pet smart but I find the best are the combo thermometer and hygrometer, its a little more expensive but it gives u both readings digitally so its easy to know. It also shows you the maximum and minimum of both. To test if its measure correctly humidity wise I couldn't tell you i can usually feel the difference though if it says 80% if you put your hand it you can usually feel the difference to that of 50%. The digital i find to be very accurate.
