Shelf life of Boveda left in their overwrap is 2 years. 60 gram Boveda provide hassle-free maintenance of full-size humidors and Humidor Bags. Every Boveda RH is accurate to +/- 1% in an air tight environment, which humidors are not. It's common that the actual RH of your humidor will stabilize up to 5 points lower than the Boveda RH you're using, due to humidor and ambient dryness. That's why we make Boveda in six different RH levels: 62, 65, 69, 72, 75 and 84 percent - so you can use the RH that achieves the humidity you and your cigars prefer. Unlike distilled water and PG solutions with sponges/gel/crystals/beads that will impart unwanted flavors on your cigars, Boveda's reverse-osmosis membrane only releases pure water vapor and Boveda will never damage anything through direct contact. Once you smoke a cigar stored with Boveda, you'll finally enjoy it exactly as the master blender intended.