Product review (1 stars): Innacurate Humidity Reading, Calibration Does Not Work
I compared this unit with a "Western Humidor Caliber III" hygrometer which I had tested in a controlled environment (75.5% Humidipak Calibration Kit). The Caliber III unit was dead-on which surprised me since I only paid $20 for that. The Extech was off by between 8% to 10%. The Extech has a calibration screw in the back so I tried calibrating it to match my other hygrometer but the screw doesnt even do anything!!! It just pointlessly TURNS! The temperature however was accurate. FINAL THOUGHTS: I'm buying another Caliber III Hygrometer and returning this one. The Caliber III is accurate within 1% Relative Humidity.