Having been in the industry more than 25 years, Boveda is a trusted and experienced brand in relative humidity control. But what does that even mean? Relative humidity (RH) refers to the percentage of humidity within an environment. In other words, it answers the question, \'how moist or dry is the air?\' Boveda\'s founders & scientists discovered that the right RH has a huge impact on an item\'s aroma, flavor & construction. Using Boveda, youll maintain a precise moisture level, which keeps your natural hand-rolled items fresh. No more mustiness. You can even use a Boveda pack to revive dry items. It takes just seconds to protect your items with Boveda. Use one Size 320 humidifier packet for every 100 TOTAL items your humidifier box can store. Just slip a Boveda in with your hygrometer (hygrometer is optional); close the container; & forget about the pack until it starts to get hard. Once it does, just switch it out with a replacement pack. If this Boveda doesnt fit in your container, you can remove the Size 320 from its outer cardboard box. Just make sure the packet doesnt get pinched or crimped when you close the containers lid. Or keep the Size 320 in its outer cardboard box-it provides protection & stability-& use it with a Boveda Mounting Plate (available separately). The box attaches to the plate, so you can affix the Size 320 to the lid, shelf or side of your container to lift humidity packs up & out of the way to make more room for what you\'re storing. Each Boveda 72 RH Size 320 can last you up to 4 months. In a 25-count humidifier box, the Size 320 provides protection for up to 1 year! Its lifespan depends on how often you open the container, how airtight your humdifier box is and how dry or humid the climate you live in is. Just a few hours without 2-way humidity control can affect the flavor & character of hand-rolled premiums. Subscribe & Save to get Boveda replacement packs sent to you automatically to keep your items fresh. Proudly Made in the U.S.A.