Product DescriptionThe D'Addario Humidifier 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. Unlike Refillable Humidifiers, The Humidity System Provides True “Two-Way” Purified Humidity Control By Adding And Removing Moisture On Demand. No More Manual Adjustments Based On Seasonal Changes, Geographic Locations, Temperature, Or Other Factors. The Humidity Kit Comes With 3 Humidifier And A Soft Mesh Pouch That Will Not Harm Your Instrument'S Finish. Humidipaks Last Between 2 And 6 Months And Should Always Be Kept In A Sealed Environment Like A Hard-Shell Case. Once The Humidifier Become Firm, Discard And Replace Using The 3 Refills That Come In The Humidity Replacement Pack (Pw-Hprp-03). D'Addario Is Known For Innovative, Problem-Solving, Quality Musical Accessories, Offering A Complete Line Of Award-Winning Accessories Including Cables, Picks, Tuners, Capos, Straps, Humidifiers, Maintenance Tools And More. The Planet Waves 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. Unlike Refillable Humidifiers, The Humidipak System Provides True Two-Way Purified Humidity Control By Adding And Removing Moisture On Demand. No More Manual Adjustments Based On Seasonal Changes, Geographic Locations, Temperature, Or Other Factors. The Humidipak Kit Comes With 3 Humidipaks And A Soft Mesh Pouch That Will Not Harm Your Instrument'S Finish. Humidipaks Last Between 2 And 6 Months And Should Always Be Kept In A Sealed Environment Like A Hard-Shell Case. Once The Humidipaks Become Firm, Discard And Replace Using The 3 Refills That Come In The Planet Waves Humidipak Replacement Pack (Pw-Hprp-03). Planet Waves, Part Of The D'Addario Family Of Brands, Is Known For Innovative, Problem-Solving, Quality Musical Accessories. Planet Waves Offers A Complete Line Of Award-Winning Accessories Including Cables, Picks, Tuners, Capos, Straps, Humidifiers, Maintenance Tools And More.From the ManufacturerThe Planet Waves 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. Unlike refillable humidifiers, the Humidipak system provides true “two-way” purified humidity control by adding and removing moisture on demand. No more manual adjustments based on seasonal changes, geographic locations, temperature, or other factors. The Humidipak Kit comes with 3 Humidipaks and a soft mesh pouch that will not harm your instrument's finish. Humidipaks last between 2 and 6 months and should always be kept in a sealed environment like a hard-shell case. Once the Humidipaks become firm, discard and replace using the 3 refills that come in the Planet Waves Humidipak Replacement Pack (PW-HPRP-03).Planet Waves, part of the D'Addario family of brands, is known for innovative, problem-solving, quality musical accessories. Planet Waves offers a complete line of award-winning accessories including cables, picks, tuners, capos, straps, humidifiers, maintenance tools and more.