Based on the same design as Planet Wave's Guitar Humidifier Pro, the Ukulele Humidifier Pro has been sized to fit inside the instrument's soundhole and protect it from the driest conditions by utilizing a specialized hydrophilic sponge, which can hold more than twelve times its dry weight in water. A rubber cap provides a tight seal and is easy to remove, allowing you to peak in on the sponge without removing the entire unit from the soundhole, so you can make sure the sponge is still moist and protecting your ukulele from cracks, shrinkage, and warped necks. The humidifier is safely suspended within the soundhole by the strings, which prevent the unit from touching the body and preserve the finish, all while releasing moisture in a slow and even manner.