The Martin Humidifier is made from the finest non-vinyl and non-allergenic material. Soak the humidifier in water. The internal resin has the ability to hold 10 times its weight in water, and slowly releases moisture to create the proper humidity. Use of a humidifier will protect your guitar from warping, cracking, or ungluing and keeps it sounding its best. These devices are a small price to pay to protect a bigger investment.