Size 4 Boveda 2-Way Humidity Control is perfect for small medicine containers, small bags and pre-roll tins. Boveda is precise humidity control for herbal medicine, which restores and maintains humidity to create a protective monolayer of water molecules over trichomes, so you can Save the Terps with the original terpene shield. Experience for yourself how much better cannabis is with Boveda. Choose from 58% or 62% RH.