Plenum Fan Wheel Type Backward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 27 3/8 in Airflow @ 0.000 in SP 11 437 cfm Airflow @ 0.250 in SP 11 146 cfm Airflow @ 0.500 in SP 10 854 cfm Airflow @ 0.750 in SP 10 556 cfm Airflow @ 1.000 in SP 10 238 cfm Airflow @ 1.250 in SP 9 921 cfm Airflow @ 1.500 in SP 9 535 cfm Airflow @ 1.75 in SP 9 127 cfm Airflow @ 2.000 in SP 8 646 cfm Airflow @ 2.500 in SP 7 495 cfm