VEVOR Inline Duct Fan, 807 CFM 8 inch EC Motor Ventilation Fan with 3-Speed Circulation, 10-Speed PWM Controller, Timer-Controlled Operation, Cooling for Grow Tents, Indoor Gardening, Hydroponics

The maximum airflow of the 8-inch model is 807 CFM. To estimate relative airflow, multiply this by the percentage of the airflow level: Level 1: Approximately 10% of maximum airflow; Level 2: Approximately 20% of maximum airflow; Level 3: Approximately 30% of maximum airflow; Level 5: Approximately 50% of maximum airflow; Level 10 (maximum): 100% of maximum airflow.