What is the difference between Free Air and Boosted Air?Free air is the air volume output from a fan, expressed in Cubic Feet per Minute (CFM) when the fan is not connected to any ductwork, pipes, louvers or other items that would interfere with the free flow of air from the fan.Boosted Air is the maximum airflow that can be passed through an In-Line Duct Fan in CFM before this fan, installed in a