I have 3 of the digital hygrometers. I calibrated them with the with the one step calibration kit. They are within 1% of where they are suppose to be. I put all 3 in my desktop humidor with 2 69% bovedas just to make sure they are all reading the same. 2 of them are within 1%, the other is 4 or 5% off. It reads 65 while the others read 68 and 69. But when I put it back in the bag to re calibrate it, it is at 75%, right where it is suppose to be. I don't understand how it can be that far off when it is calibrated right?