Exhaust/Supply Fan Assembled Assembled Blade Diameter 18 in Blade Material Aluminum Drive Type Direct Drive Duct Diameter 18 1/2 in Exhaust Airflow @ 0.000 in SP 3 477 cfm Frame Finish Galvanized Frame Material Steel Guard Type None Includes Reversing Switch Includes Dehumidistat No Maximum Noise Level 18.4 sones