5,600 CFM from a blade that is belt driven by an infinitely variable speed motor. The large propeller size opening is connected to 2 20 inch ducts and 2 20 inch ceiling openings.

This is the first time a noisy ceiling mounted whole house fan has ever been mounted high in an attic to reduce the noise in the room below. This gives you the advantage of a larger propeller that moves more air combined with the ducts that allow this loud propeller to be silenced.