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Fits in 2-Inch x 4-Inch ceiling or wall construction 80 CFM ensures ample air movement Greater than 50 CFM at 0.25-Inch static pressure meets ASHRAE 62.2 local ventilation requirements Only 1.1 sones for extremely quiet operation (quieter than equivalent competitive models) 4-Inch oval or 3-Inch round duct for installation flexibility (not available in competitive models)