Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 20 in Airflow @ 0.250 in SP 8 489 cfm Airflow @ 0.500 in SP 8 338 cfm Airflow @ 0.750 in SP 8 181 cfm Airflow @ 1.000 in SP 8 017 cfm Airflow @ 1.250 in SP 7 844 cfm Airflow @ 1.500 in SP 7 664 cfm Airflow @ 2.000 in SP 7 272 cfm Airflow @ 2.500 in SP 6 829 cfm Airflow @ 3.000 in SP 6 314 cfm Airflow @ 3.500 in SP 5 690 cfm Airflow @ 4.000 in SP Not Applicable