Product review (5 stars): Makes a HUGE DIFFERENCE vs the standard cheap flappy thingy!
We had a noticeably cold laundry room near our dryer, and this vent closure makes a HUGE DIFFERENCE vs the cheap useless plastic flappy vent cap!

I'm a little ashamed about how happy I am with this product, because after all - it's just a dryer vent cap. We originally had one of the standard cheap flappy thingies outside which was doing virtually nothing, especially since the darn thing was half clogged open with lint. When it was really cold outside, our laundry room felt as cold as if a window was open (it has no windows). Dry clothes we left inside after the dryer was finished would be so cold they almost felt wet. Not only was the 4-inch diameter hole leaking tons of heated air, freezing the crap out of the dryer probably hurt its efficiency too. But, this product fixed all these problems!!!! For an easy 10-15 minute installation (most time spent chipping away excess mortar from previous sloppy installation), our laundry room no longer feels like a meat locker.

Pros:
Surprisingly easy install, most time consuming part was brick wall.
Saves money and energy! (Couldn't find actual figures)
Makes the laundry room much more comfortable.
Laundry room no longer a meat locker in winter!
Looks kinda sci-fy outside.
Brick wall gave me an excuse to use my hammer drill!

Cons:
Can no longer use the freezing cold of the laundry room as an excuse to avoid doing laundry.
I'm a little ashamed at how excited I got about the difference this made, I may need to get out more.