Keeping your instrument safe and playable has never been easier, thanks to D'Addario Humidipak. Using Boveda’s two-way humidity control technology, Humidipak automatically adds or removes moisture to maintain an ideal humidity level of 45%-55% RH inside your instrument case. Humidipak Features:   Revitalizes extremely dry guitars and cases Quickly and safely restores relative humidity Reverse osmosis membrane releases pure water vapor Eliminates the guesswork of maintaining your instrument’s proper humidity level