Prevent damage and cracking from extreme temperatures and low humidity with the RDM Guitar Humitron Humidifier. Humitrons are made from the finest non-vinyl, non-allergenic resin. Simply submerge the humitron in water for several seconds, wipe off the excess, and place inside your instrument. The water-suction stems within the Humitron absorb water ten times their weight and slowly release it through the holes.