Taking inspiration from the popular Guitar Humidifier Pro, the D'Addario Ukulele Humidifier Pro is designed to fit in the soundhole of a ukulele. Just like its guitar counterpart, this humidifier houses a hydrophilic sponge that holds up to 12x its weight in water. That means the sponge needs to be hydrated less often, thus keeping the ukulele humidified for a longer amount of time and extending the instrument's lifetime. This is a great option for any player looking to humidify their ukulele with ease.