D'Addario Humidipak Maintain Automatic Humidity Control System

Features

• The only maintenance-free, two-way humidity control system for guitar. 
• Automatically maintains the optimal 45-50% relative humidity level within your instrument case by adding or depleting moisture as necessary. 
• Packets last between 2-6 months and should always be kept in a sealed case.
• Includes: 1 Headstock Pouch, 1 Soundhole Pouch, 3 Maintain Packets