MOISS2-GC2 is the guitar humidity controller for classic guitars and able to fit in 85mm diameter soundhole. MOISS2-GC2 humidity controller is the first of its kind to both absorb and release moisture, depending on the humidity level, which is displayed to the user. Manufactured in Japan, MOISS2-GC2 is designed to absorb twice as much moisture as silica and does so in five-times the speed. It keeps relative humidity at 50%. Lifetime is 1-2 years under normal environment.