Product review (1 stars): Cheap price, cheaply made
I bought two of these HTC-1 humidity testers from two different vendors, and was not pleased with either purchase.  Both were not accurate in the least.  I have a very expensive humidity tester that is accurate and has been properly calibrated, and these two cheap HTC-1's were always 5-10% different, and even from each other.  Even when set side by side for hours, they couldn't even agree on the temperature.

Don't waste your money.  Unless you solely want this for a clock.  In that aspect, it seemed to keep time pretty well.