G-LEAF 6 Inch 312 CFM Speed Adjustable Duct fan 6'' Duct Booster Fan Design With Adjustable Two Speed Motor. Low Noise: Adopt Two-Sides Banlances On Fan,The Moust Loudly Nosie 33 db (Max Value) Repeated Testing, The Fan Life Time More Than 30000 Hours. 312 CFM Big Air Flow, High Stability, High Efficiency. Keeping The Best Banlance Betwwen Air flow and Noise