Blower Wheel Type Forward-Curved Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 20 in Airflow @ 0.125 in SP 5 861 cfm Airflow @ 0.250 in SP 5 508 cfm Airflow @ 0.375 in SP 5 161 cfm Airflow @ 0.500 in SP 4 796 cfm Airflow @ 0.750 in SP 3 865 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