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 2 130 cfm Airflow @ 0.500 in SP 1 659 cfm Maximum Inlet Air Temperature 104 Degrees F Shaft Diameter 1 in Bearing Type Ball Sound Level 5.6 sones @ 0.250 in SP and 5 ft Frame Material Galvanized Wheel Material Aluminum Inlet Diameter 11 3/4 in Rough Opening Height 22 1/2 in