The DAddario Reed Vitalizer single refill offers maintenance-free reed storage. The Humidipak technology uses two-way humidity control to prevent warping and keep your reeds stable in any weather conditions. Reed Vitalizer Humidity Control Packs will last 45-60 days. When the pack becomes hard simply discard and replace with a new pack. This refill has a humidity level of 72 which means that minimal wetting will be required.