Our newest humidifier is designed especially for your ukulele with two unique features:1. A mounting system that allows the humidifier to hang horizontally inside the ukulele rather than vertical (like the guitar humidifier).2. A humidity output of about 50% of the blue Oasis guitar humidifier, to accommodate the ukulele's smaller instrument size. This also allows the humidifier to last twice as long between refills.The exclusive Oasis® design of all our humidifiers makes the Oasis® Ukulele Humidifier easy to see when to refill, provides long-lasting humidification, ensures no leakage due to overfilling, and promises two levels of leak protection.Because tap and bottled water have dissolved minerals that can clog the liner, distilled water is recommended to extend the useful life of your ukulele humidifier. Most instruments only need seasonal humidification. Typically, the humidity drops in the fall and rises in the spring. When the spring arrives, we recommend that you remove the humidifier, wash all of the crystals out, and leave the cap loosely on the humidifier. If you do not remove the crystals and loosen the cap, the humidifier will shrink up, dry up and the crystals will stick together. In the fall, it is easy to damage the lining of the humidifier when trying to restore it to shape. The lining is only 1/1000th of an inch thick and can be damaged easily if it sticks to itself and the crystals, when the humidifier shrinks up and dries up if the lid is left on tight.