Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 18 1/4 in Airflow @ 0.250 in SP 4 364 cfm Airflow @ 0.500 in SP 4 131 cfm Airflow @ 0.750 in SP 3 876 cfm Airflow @ 1.000 in SP 3 595 cfm Airflow @ 1.250 in SP 3 269 cfm Airflow @ 1.500 in SP 2 809 cfm Airflow @ 2.000 in SP Not Applicable Airflow @ 2.500 in SP Not Applicable Airflow @ 3.000 in SP Not Applicable Airflow @ 3.500 in SP Not Applicable