Blower Wheel Type Forward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 20 in Airflow @ 0.125 in SP 8 518 cfm Airflow @ 0.250 in SP 8 254 cfm Airflow @ 0.375 in SP 8 002 cfm Airflow @ 0.500 in SP 7 755 cfm Airflow @ 0.750 in SP 7 261 cfm Airflow @ 1.000 in SP 6 743 cfm Airflow @ 1.250 in SP 6 158 cfm Airflow @ 1.500 in SP 5 405 cfm Airflow @ 2.000 in SP Not Applicable Airflow @ 2.500 in SP Not Applicable