Features: 1.Science and technology to prevent smoke, block harmful substances in the flue to protect the health of family members 2.When exhausting smoke, the wind will automatically turn on the oil and the fan blades will only flow out. When not draining, the gravity spring case is closed to prevent oil smoke from entering the public flue 3.No need to worry about changing diameters, there are five types of diameter reducing rings, which are suitable for most range hoods 4.Butterfly-type bionic design, open with the wind, straight-through smoke exhaust, unobstructed 5.Slope gravity self-sealing, 17° slope gravity self-closing design, good sealing Notice: Actual color may be slightly different from the image due to different monitor and light effect Please allow 1-3mm deviation due to manual measurement Package List: 1 set x Range Hood Check Valve