Automatically maintains the 70% humidity levels required to keep cigars at their freshest. The humidification process is actually controlled by the nontoxic chemicals we charge into the Crystals in the factory. You never have to add anything but plain distilled water again. The crystals swell up when they have water in them and shrink when they need more, takes all the guess work out of it. The size is perfect to stash a few in different parts of your humidor. Priced per tube