Tubeaxial Fan, Drive Type Direct Drive, Includes Drive Package Yes, Includes Motor Yes, Blade Diameter 18 in, Nameplate Voltage 115V AC, Phase 1, Motor Horsepower 1/2 hp, Airflow @ 0.000 in SP 3,938 cfm, Maximum Noise Level @ 5 Feet 25 sones, Assembly Assembled, For Air Type Clean Air, Blade Material Aluminum, Housing Material Steel, Number of Blades 6, Number of Speeds 2, Motor Enclosure Totally Enclosed Air Over, Standards AMCA Sound and Air, UL Listed, Bolt Circle Diameter 19 7/8 in