Love Your Instrument—for effortless humidity protection, use Boveda. Having been in the industry for 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 in my instrument case?' Boveda's founders & scientists discovered that the right RH has a huge impact on a wood instrument's performance & sound & safeguarding its construction. Using Boveda, you'll maintain a precise moisture level between 45 and 55% RH—no more mustiness in your instrument case. Just slip a Boveda into a Fabric Holder (available separately), position it in your case & forget about the pack until it starts to get hard. Once it does, just switch it out with a replacement pack. (This multi-pack of Boveda 49 RH Standard contains 12 individually wrapped replacement humidity control packs.) Each pack can last you up to 6 months. Its lifespan depends on how often you open your case, how airtight your case is, & how dry or humid the climate you live in is. USE BOVEDA 49% RH STANDARD HUMIDIFIER/DEHUMIDIFIER PACKS in an instrument case to maintain the right humidity for: GUITARS, including acoustic, electric, electric bass, guitarrón, hollow-body, nylon string & semi-hollow body; FRETTED INSTUMENTS, including banjo, mandolin & ukulele; STRINGS, including cello/violoncello, double bass/upright bass, hollow-body bass, viola & violin; & WOODWINDS, including bass clarinet, bassoon, clarinet & oboe. Subscribe & Save to get Boveda replacement packs sent to you automatically. Proudly Made in the U.S.A.