It is essential to maintain a proper moisture level if your guitar is stored in an area prone to severe dryness/and or cold (such as a heated home). GroverÂ®'s guitar case humidifier helps to prevent adverse effects such as bad string action, buzzing, protruding fret ends, cracking, top-sinking, and other damage caused as a result of dryness. Made of soft latex which is harmless to all instrument finishes, these humidifiers release moisture to maintain proper humidity levels. Includes a cover to seal the sound hole during use. Easy to follow instruction and a user friendly humidity gauge are included.