Blower Wheel Type Forward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 20 in Airflow @ 0.125 in SP 6 369 cfm Airflow @ 0.250 in SP 6 039 cfm Airflow @ 0.375 in SP 5 718 cfm Airflow @ 0.500 in SP 5 390 cfm Airflow @ 0.750 in SP 4 645 cfm Airflow @ 1.000 in SP Not Applicable Airflow @ 1.250 in SP Not Applicable Airflow @ 1.500 in SP Not Applicable Airflow @ 2.000 in SP Not Applicable Airflow @ 2.500 in SP Not Applicable