Here's the round version of the HygroSet Adjustable Hygrometer.  Very practical as readings can be adjusted after each calibration.  You can adjust the humidity displayed by 1% per click of the adjustment knob.

This hygrometer is the most accurate way to measure the humidity in your humidor!  Perform the 75% salt test, adjust to the correct humidity and you're done!

This adjustable hygrometer is the first of its kind.  Readings can be adjusted after each calibration, just turn the adjustment knob and change the humidity displayed by 1% per click.

You'll never have to wonder about the accuracy of your hygrometer again!  Just perform the salt test, adjust to the correct humidity and you're done!