D'Addario, in collaboration with Humidipak, brings you the first two-way humidity controller that maintains a constant 45% relative humidity level. The Humidipak humidification system completely eliminates all the guesswork and anxiety of maintaining your musical instrument's proper humidity level. No more guessing if or when to refill the humidifier and worrying about drips or mess. Unlike all refillable humidifiers, the Humidipak acts as a gauge because it provides true "two-way" purified humidity control. It adds or reduces moisture only as needed to maintain 45% RH—the ideal climate for wooden instruments such as acoustic guitars.

Just place two packets in the double pouch. Put the double pouch over your D and G strings and let it hang down into the soundhole. Place the third packet under your guitar's headstock in its case. Close the case and you're done. The packet will last anywhere from 2–6 months, depending on the humidity where you are. When the packet become firm, discard and replace. The D'Addario Humidipak humidity controller is as simple as that.