Simply place your hygrometer inside the bag, close the zipper, and wait 24 hours. A perfectly-calibrated hygrometer will read 75% RH. If your hygrometer reads above or below 75%, adjust the calibration by the number of percentage points it is off from 75%.
Completely maintenance free – no activation required. Easy to use.
Bag Dimensions: 4.5-Inch x 9-Inch.
Lasts approximately one year, good for multiple calibrations. Shelf life before opening is a minimum of 2 years.