D’Addario Humidipak is the only maintenance-free, two-way humidity
control system for guitar. It automatically maintains the optimal
45%-50% relative humidity level within your instrument case, eliminating
the guesswork and potential mess related to refilling a humidifier. No
more manual adjustments based on seasonal changes, geographic locations,
temperature, or other factors. Note: Humidipak is designed for
restoring and maintaining instrument humidity. This product is not
intended for dehumidification in high humidity environments.