VIVOSUN Inline Duct Fan 150mm Exhaust Fan 688m³/h with E12 Speed Controller and Fully Programmable PWM Controlled EC Fan AeroZesh S6 for Grow Tent VentilationEfficient Ventilation: The AeroZesh S6 has powerful performance with airflow at 405 CFM to create optimal ventilation for your grow space; A PWM controlled EC fan with mixed flow design that is fully adjustable and responsive to the environment E12 Speed Controller: Ten fan speeds controlled by PWM can be selected by you; Turn off and then on again, backup memory can remember the speed set before the last shutdown; Three ON OFF cycle mode can achieve