Shutter Mount Exhaust Fan Assembled Assembled Blade Diameter 20 in Blade Material Aluminum Control Type Pull Chain Drive Type Direct Drive Duct Diameter 20 3/8 in Exhaust Airflow @ 0.000 in SP 2 235 cfm For Cut-Out Height 20 1/2 in For Cut-Out Width 20 1/2 in For Maximum Wall Thickness 5 1/2 in For Minimum Wall Thickness 3 in Frame Material Aluminum Guard Finish Chrome Guard Material Steel Guard Type Exhaust Housing Material Aluminum Steel Housing Finish Galvanized