Ditto on the above. I used the gel crystals and always had a higher Rh than I wanted the beads fixed the problem in a couple days. I purchased 4 humis of varying size before getting my cooler and every analog hygrometer that came with them was off by 8 percentage points or more. I definitely recommend a digital hyrometer. The two I got from ebay were only off by two points though the one from heartfelt was off by 9.