Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 20 in Airflow @ 0.250 in SP 5 551 cfm Airflow @ 0.500 in SP 5 306 cfm Airflow @ 0.750 in SP 5 035 cfm Airflow @ 1.000 in SP 4 727 cfm Airflow @ 1.250 in SP 4 369 cfm Airflow @ 1.500 in SP 3 934 cfm Airflow @ 2.000 in SP Not Applicable Airflow @ 2.500 in SP Not Applicable Airflow @ 3.000 in SP Not Applicable Airflow @ 3.500 in SP Not Applicable