Plenum Fan Wheel Type Backward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 30 1/2 in Airflow @ 0.000 in SP 15 157 cfm Airflow @ 0.250 in SP 14 817 cfm Airflow @ 0.500 in SP 14 475 cfm Airflow @ 0.750 in SP 14 134 cfm Airflow @ 1.000 in SP 13 765 cfm Airflow @ 1.250 in SP 13 394 cfm Airflow @ 1.500 in SP 13 016 cfm Airflow @ 1.75 in SP 12 538 cfm Airflow @ 2.000 in SP 12 059 cfm Airflow @ 2.500 in SP 10 889 cfm