Product review (5 stars): No Need To Calibrate - Worth The Money
This is a very good hygrometer/thermometer. I use it in my cigar humidor/cooler in conjunction with another digital hygrometer so I always know what's going on. I have used quite a few analog hygrometers and I find them to be unreliable in the long term. These digital hygrometers are much better in my opinion and they come calibrated so there's no need to recalibrate (you only need to do this with sensitive analog hygrometers). The accuracy is pretty decent, well within +/- 5 which is fine for the low cost. I've tested this Qooltek hygrometer in the heat outside and inside the humidor/cooler and it does a great job with accuracy.