This hygrometer from Oasis is a great tool for monitoring the humidity and temperature in the room where your instrument is kept, or inside the case with the instrument. Extremes of humidity or dryness can be dangerous to musical instruments, and knowing the humidity allows you to decide if humidification or dehumidification is necessary in your environment.
This case humidifier made by Oasis fits in almost any instrument case. A choice of two attachment methods makes it easy to use. The humidifier shrivels up and looks dry when it needs more water, making it simple to monitor. If your climate is dry, this is a great way to help keep your instrument happy. It includes a handy syringe for filling it without removing it from the case.
For more information, please read our PDF download about Humidity, Dryness and Musical Instruments.