Boveda - 49% Relative Humidity, Size 8

Precise humidity control for your ukulele. The Boveda is a two-way system – meaning that it will either absorb moisture from the environment or release moisture into the environment depending on what the ukulele needs at the time.  
Recommend using 2 per case, one under the neck or headstock and one on the strings.  Depending on your instrument case and its surrounding environment, you can expect Boveda to last from 2 to 6 months.