Product review (1 stars): Seemed accurate, but is not!
This hygrometer is very accurate for both inside and outside use.  It helped me detect a high level of humidity in my room which is probably causing some health problems related to mold.  This product was very cheap and well worth the price.  Thanks!

The temperature gauge, here in the US, is not too helpful since we don't use Celsius.  But I do appreciate learning Celsius!

Update: After using it for a few weeks, I got a dehumidifier in my room.  The dehumidifier said that the humidity in the room was around 40%, not the 60-70% that this hygrometer said.  I tested the hygrometer by putting it outside (so that I could compare it to the official humidity according to the weather station) and the hygrometer was always wrong.  It seems that it never leaves the 50-70% range.

This being said, I can no longer recommend this product.