Review on 4-inch Deflecto Dryer Vent, Galvanized Vent Hood with Wide Mouth Design, Silver Finish (GVH4NR) by Hassan Tomlinson

Not sure about the description. To clarify, it's a vent tube, shroud, and valve at the closed end that keeps critters and drafts out. There is nothing more. Seems to be well made and will likely last a very long time. The damper works by gravity and is very light. Outside wind or positive air pressure inside the house will force it open. In my application, the existing opening was uneven, causing the wing to remain ajar and flap in the wind. Between this and the lightness of the valve, I decided to siliconize two very small but powerful magnets on the outside/back of the valve. The damper now closes flush and very tight. The fan blows with a force incomparable to the force of magnets (this modification is not recommended for range hoods). Very happy with this item.