I discovered this product in an appliance dealer showroom, and was pleasantly surprised with the compact size for the cfm rating of 390.  That rating keeps it low enough so that makeup air is not required by the IRC code, yet will still move a large amount of air.  It's very quite at the lower settings.  The high and max settings get a little loud, even with the recommended 8" duct, but when you move that much air, that's to be expected.