Just like its name implies, this humidifier allows the user to manually adjust the flow of humidity.  One benefit of evaporation-adjustable humidifiers is that the size of the humidifier does not need to be professionally synchronized with the size of the humidor.  The user can simply make small adjustments to the humidifier to increase or decrease the flow of moisture.  Another benefit is that a larger humidifier can be placed in a small humidor and adjusted to emit less moisture.  This will greatly lengthen the time between refills and give you greater peace of mind.