Product review (1 stars): Don't buy this if you want to check the outside ...
Don't buy this if you want to check the outside or inside humidity !! Today, July 20, 2015 it shows outside humidity at 42%. It rained this morning over 2 inches. It's summer in the St. Louis area. It is 79 muggy degrees outside !! It should read about 88%. You can calibrate inside humidity, but not outside. What a high priced piece of junk !!!!!