In-Line Duct Blower Wheel Type Backward-Inclined Drive Type Belt Drive Includes Drive Package Yes Assembly Unassembled Wheel Diameter 18 in Airflow @ 0.000 in SP 4 651 cfm Airflow @ 0.125 in SP 4 608 cfm Airflow @ 0.250 in SP 4 565 cfm Airflow @ 0.375 in SP 4 511 cfm Airflow @ 0.500 in SP 4 452 cfm Airflow @ 0.750 in SP 4 326 cfm Airflow @ 1.000 in SP 4 187 cfm Airflow @ 1.250 in SP 4 034 cfm Airflow @ 1.500 in SP 3 866 cfm Airflow @ 2.000 in SP 3 468 cfm