Shutter Mount Exhaust Fan Assembled Assembled Blade Diameter 18 in Blade Material Aluminum Drive Type Direct Drive Duct Diameter Not Applicable Exhaust Airflow @ 0.000 in SP 1 785 cfm For Cut-Out Height 19 in For Cut-Out Width 19 in For Maximum Wall Thickness 6 in For Minimum Wall Thickness 3 in Frame Material Aluminum Guard Finish Powder Coated Guard Material Steel Guard Type Intake Housing Material Aluminum Steel Housing Finish Powder-Coated Includes Intake Guard