4" Cape Backdraft Damper

I replaced a butterfly damper with this. The cape damper is far quieter (far less turbulence), but seems to adequately block air movement in the other direction.

I like the Cape dampers because they are quiet. The only thing to watch is that they are sized for a 4 inch duct and are difficult to slide into the "slightly undersized" ducts that come attached to siding vents. Was able to slide it in after removing the foam sealing ring around the outside.

Bought this product as an extra layer of protection from the cold. The vent outlet is located on the windy side receiving Lake Superior winter winds so I wanted to be sure to minimize the chance cold drafts making their way in. The backdraft damper fits very snug into the vent. You just need to work it in making sure the small foam ring goes in cleanly. Once it is in I couldn't push it further by hand, so I used the crimped end of the next piece of solid vent to move to further in. It comes easy enough by hand. (I'm pretty sure it would be an easy fit into flexible duct). Hopefully that foam ring will hold up for some years. It seems to be a well built product, solid with a good gauge. Looking forward to see how it performs in those winter winds.

This is a simple and effective way to seal a bathroom fan vent without adding excessive backpressure.

This damper is a little different from the typical butterfly type. While I would generally prefer a metal damper, this one has a smaller diameter, and was able to squeeze into the roughly zero clearance application that I needed it for.

Good customer service

I am about to install my Second damper in a remote attic location. My hope is that it will prove more reliable than metal dampers whose vanes tend to jam due to dust inside the duct. When used at the end of an exhaust duct It should prevent flying insects & tiny birds from entering the duct. Best of all it has no metal parts that might require periodic lubrication or cleaning.

Purchased because it was spec'd for the job by an engineer but I'm unimpressed with the product. Pros: it has no mechanical or metal parts and will never rust or fail in the closed position. Cons: it will not completely close unless there is a significant push against it like a heavy wind - in a light breeze or normal operating conditions it will not close 100% like a spring loaded damper would.