Product review (5 stars): Practical design, super quiet and keeps out unwanted guests!
I purchased this dryer vent closure to replace the flimsy louvered one my contractor installed.  It was flapping constantly with just the slightest breeze and could be heard in the next room.  Besides, I was worried about vermin or bugs eventually making their way inside, not to mention the cold Chicago winter air.  This unit was a breeze to install.  It is important to understand that the lid on top is meant to stay closed.  It is supposed to be difficult to open because it should only be opened for cleaning out any lint that may accumulate which should not be often since the lint blows out through the bottom.  The way it works is that the hot air pushes an inner plastic piece up, the air and lint blow out and when the air stops blowing, the piece returns to it's resting position to block out unwanted guests and cold or hot air from the outside.  I figure this should last for some time as I have it installed up high since my first floor is about 10' off the ground and it is installed under an eave for protection from the elements.  Once we installed it, we caulked around the entire areas that make contact with the house in order to seal out any water, snow or bugs.  We just used silicone.  This unit is 100% quiet.  The unit arrived quickly.  This is a top-notch seller.  I highly recommend this unit for anyone who wants peace and quiet with the added benefit of keeping out vermin, bugs and bad weather.  It is a must-have.