Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 18 1/4 in Airflow @ 0.250 in SP 5 043 cfm Airflow @ 0.500 in SP 4 846 cfm Airflow @ 0.750 in SP 4 635 cfm Airflow @ 1.000 in SP 4 408 cfm Airflow @ 1.250 in SP 4 163 cfm Airflow @ 1.500 in SP 3 892 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