Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 36 1/2 in Airflow @ 0.250 in SP 18 989 cfm Airflow @ 0.500 in SP 18 430 cfm Airflow @ 0.750 in SP 17 868 cfm Airflow @ 1.000 in SP 17 299 cfm Airflow @ 1.250 in SP Not Applicable Airflow @ 1.500 in SP 16 115 cfm Airflow @ 2.000 in SP 14 816 cfm Airflow @ 2.500 in SP 13 288 cfm Airflow @ 3.000 in SP 11 186 cfm Airflow @ 3.500 in SP Not Applicable