Product review (3 stars): House I purchased already had these vents, so I ...
House I purchased already had these vents, so I was able to remove the flappers from the new unit and install on the old unit without having the change the vent (if I changed to a new style the vinyl siding would not have looked as nice). I think the quality of the vent is low, and the louvers are prone to warping over time - but this product was exactly what I needed for a quick fix.