Product review (3 stars): I would buy another, but ......
Simple design, like a sewage over flow popper. Three stars for materials and manufacturing, could be easily so much better. Like other reviews, adapting to your existing flex dryer line is a pain. I used an adapter made to connect two dryer flex hoses together from big box store with metal tape to secure. I think it helps keep out drafts from outside, my old louvered vent didn't shut tight so I needed to replace anyway. It is BIG but painting it to match the exterior paint made it work.