Check the listing for details. VIVOSUN T6.6 Inch 390 CFM Inline Duct Fan with Variable Speed Controller. Condition: Open box. Listed at 79.99 USD. VIVOSUN T6 6 Inch 390 CFM Inline Duct Fan with Variable Speed Controller HVAC Blower for Ventilation Energy-Efficient Ventilation: This powerful blower with a fan speed of 2550 RPM can create an air flow of 390 CFM; It combines the features and benefits of axial and centrifugal fan, effectively circulating airLow Noise Level: The durable fan blades revolve smoothly and powerfully, which helps collect airflow volume and cut noise output; A less than 34 dB noise level will not disturb your workAdjustable Speed: A stepless speed controller on the power cord enables the fan to run at different speeds; With this speed switch, you can adjust it to the desired airflow levelEasy Installation: This duct fan is compact and lightweight so it can be installed in small areas; Comes with an installation bracket indicating the direction of the airflow; Removable duct ends with locking tabsVersatile Applications: Suitable for industrial, household and horticulture ventilation applications; It can quietly and efficiently moving large volumes of air throughout your ventilation system