Features:1. High Performance Motor: The duct fan adopts 6-stage variable frequency brushless EC motor that produces 160CFM strong airflow using 18Watt/hour only.2. Stepless Speed Controller: The included PWM speed controller with 5m connection cable can accurately adjust the fan's speed from 0% to 100%.3. Low Running Noise: The fan will not produce additional noise and hum when running from 0% to maximum speed.4. Aluminum Outer Case: Better pressure resistance and durability, low maintenance costs, suitable for harsh environments.5. Premium Material: The turbine blades are made of superior PBT material, not only environmental protection but also fire prevention.Specification:Voltage: AC 220V (Plug NOT Included)Power: 18WDuct diameter: 4 inchSpeed Adjustment: 0-100 AdjustableAir volume: 160CFM, 275m3/hMaximum speed: 5000 RPMNoise range: 0-56.8dBColor: BluePackage list:1 x Duct Fan1 x Speed Controller1 Set of Mounting AccessoriesNote:1. Due to the difference between monitors and light effects, the pictures may not reflect the actual color of the item.2. Please allow slight error due to manual measurement. Thanks for your understanding..