D'Addario brings its patented Humidipak Maintain system, powered by Boveda's two-way humidity control technology, to orchestral string instruments. This system maintains a consistent 45-50% relative humidity inside your case, protecting against cracks, warping, and open seams. The Humidipak automatically adds or removes moisture as needed, with no water or refills, and no guesswork. To use, just place the Humidipak packet in the included pouch, put it inside your case, and let the system handle the rest. NOTE: Humidipak replacement packets must always be used with the provided containment pouch. Maintenance-free for three months.