Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 20 in Airflow @ 0.250 in SP 6 134 cfm Airflow @ 0.500 in SP 5 917 cfm Airflow @ 0.750 in SP 5 681 cfm Airflow @ 1.000 in SP 5 421 cfm Airflow @ 1.250 in SP 5 131 cfm Airflow @ 1.500 in SP 4 802 cfm Airflow @ 2.000 in SP 3 933 cfm Airflow @ 2.500 in SP Not Applicable Airflow @ 3.000 in SP Not Applicable Airflow @ 3.500 in SP Not Applicable