Review on Geburun Mini Indoor Thermometer and Humidity Gauge - Battery-free Room Thermometer and Humidity Monitor for Home, Study, and Basement by Keith Iverson

I order this pair and both were at perfect temperature but the humidity was off on one of them. I emailed customer service and they immediately refunded my money. What was wrong was far away - somewhere around 10 or 15 percent. The company informed me that this can sometimes happen while they are in stock prior to purchase. Anyway, the one that was far away is only 2 percent cheaper a few weeks later. So it looks like he tends to be right. So if you have one that isn't working, maybe give it a few weeks to see if it gets used to itself. Now I feel guilty for getting a refund as I think it's great (I'm only subtracting 2% from what is now little). In any case, I recommend them for their easy readability and excellent customer service.