Product review (1 stars): Garbage!
A broken clock would be more accurate. At least it's right twice a day. From the beginning, this thing read humidity low, about 5-10% lower than other sensors that agreed with each other. Steadily, this inaccuracy increased until it only reads 10% humidity at all times. After about a month.
Other similar hygrometers are working great for me. DON'T WASTE YOU TIME OR MONEY ON THIS.