Product review (4 stars): It is what it is
I bought this because I needed an in expensive hygrometer for a spare cigar humidor. I calibrated it with a 69% boveda pack and it read 86% r/h. Just to be sure I took it out and put another hygrometer that is very accurate and it read within the 1% variation (68%). I tried to recalibrate it again and it still read 86%. So for $8 I'll deal with subtracting 17%, but it's really annoying.
Update 9/16/17: after reading my review the company contacted me and decided to send a replacement asset no cost. I received it a couple days ago and calibrated it with the same 69% boveda pack. It read 71%, which is within the +/-2% I was looking for. I upgrade my rating to 4 stars because of the service and the product.