Maintaining your instruments humidity level is essential to preserve its playability, sound and integrity. The Planet Waves Small Instrument Humidifier releases moisture evenly and slowly inside your instruments case to maintain the proper humidity level, preventing cracks, warping, and shrinkage to your instrument. Using the humidifier is as easy as moistening the sponge when it becomes dry. The small instrument humidifier can also be used in conjunction with the traditional Planet Waves Guitar Soundhole humidifier (GH) for acoustic guitars when your humidity is consistently 20% or lower. Get one for all of your valuable instruments. It�s the smart, easy, and affordable way to protect your investment.