Precise humidity control for wooden humidors. Boveda's patented 2-way humidity control responds to ambient conditions by adding or removing moisture to affect the enclosed environment and deliver the pre-determined humidity (RH) level printed on the pack! This product is ZERO maintenance. Once your pack becomes rigid and firm, simply replace it. 1 pack will humidify a 25 ct. humidor. For a 100 ct. humidor you would use 4 packs.