Title: Cannot calibrate
Review: I bought two of these things a few days ago. I was immediately stunned by the fact that the instructions require a third-party calibration set in order to calibrate these hygrometers (by the way, you should always calibrate a hygrometer upon purchase). Oh well, fortunately I still had the instructions for my other Xikar hygrometer which described a simple salt calibration method. Did that. One hygrometer read 10% too low and the other 5% too low. So I proceeded to the adjustment phase as described by the instruction sheet that came with the product. That is, turning the knob clockwise should have adjusted the hygrometers to read the correct values, one click at the time. Problem is, turning the knob did absolutely nothing, on both hygrometers. I read the instructions over and over, tried many times, without luck. I came to the only conclusion that the adjustments knobs simply do not work. These hygrometers are completely useless.
Is this product review negative?