Plenum Fan Wheel Type Backward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 18 1/2 in Airflow @ 0.250 in SP 2 866 cfm Airflow @ 0.500 in SP 2 575 cfm Airflow @ 0.750 in SP 2 195 cfm Airflow @ 1.000 in SP 1 650 cfm Maximum Inlet Air Temperature 104 Degrees F Shaft Diameter 1 in Bearing Type Ball Sound Level 9.3 sones @ 0.250 in SP and 5 ft Frame Material Galvanized Wheel Material Aluminum Inlet Diameter 11 3/4 in