As with all of our humidifiers, you can count on the Oasis® Three-Quarter Size Double Bass Humidifier to protect your instrument from cracking in dry winter weather by providing it with the humidification it needs without leaking or hurting your instrument. Its unique Oasis® design makes it easy to see when to refill, provides long-lasting humidification, ensures no leakage due to overfilling, and promises two levels of leak protection. Our Double Bass Humidifier is the same size as our other humidifiers, but generates substantially more daily humidity. How does it work? To accommodate the large air capacity of the double bass, two humidifiers are generally required to supply sufficient humidity. Due to the high humidity output of this humidifier, the unit should be refilled every three days. The humidifiers fit inside the double bass through the hole at the bottom of the F hole. This humidifier will not fit every double bass. The opening must be 1 ¼” or larger, so it isn’t suitable for half-size or smaller double basses but fits most three-quarter size double basses. The suspension system is completely new. An elastic cord slips over the neck of the humidifier and is held in place by both tension and the humidifier cap. The cord is knotted at the end and extends through two pieces of felt (user-installed. One piece of felt is round and fits in the F hole. The other is rectangular and fits outside the double bass keeping the humidifier from falling into the instrument. Because tap and bottled water contain dissolved minerals that can clog the liner, distilled water is recommended to extend the useful life of your humidifier.