Music Nomad MN302 Humilele Ukulele Humidifier Ukulele humidifier rests securely between strings and fits in all ukulele sound holes Ukulele manufacturers recommend humidity of their ukulele be kept between 40 to 55 percent Innovative Humid-I-Bar sponge holds 10x its weight in water and features anti-drip, no-mess material that safely releases moisture Simple-to-use, long-lasting, low-maintenance humidifier for soprano, concert, tenor, and baritone ukes Convenient quick-flip top lets you check if Humid-i-Bar sponge is wet or dry