Product review (5 stars): Great Vent for the price. Sigificant step up from the big box offerings.
Great design built with a thick, quality steel. The flapper is much better than those at the big box stores. The thickness of the metal makes for a stronger, better vent for your dryer.

This vent is not airtight, but most dryer vents are not. The flapper is very light weight, and designed to easily move out of the way of the air flow. The way the vent is mounted will prevent dryer lint from accumulating on any hinge or piece of the flapper. Great design in that respect.

Note: For my bathroom vent application I also added a separate airtight damper in line with this vent to prevent backflow. For this application I was not worried about lint getting trapped on the separate airtight damper.  (http://www.amazon.com/gp/product/B000CDAFE6/ref=cm_cr_ryp_prd_ttl_sol_9)

I purchased two of these for a dryer and bathroom vent in a basement renovation project. I'm very satisfied with the quality for the price.

I recommend taping the seam of the vent pipe to prevent moisture from escaping the pipe into the wall cavity. Taping the OUTSIDE of the vent seam will prevent loose tape from blocking flow or causing a lint trap.

Installation in brick veneer:

Installation in brick was easy using a 4" core drill. ( Using this method as opposed to a lot of small holes drilled with a hammer drill bit results in a much more water tight installation, and water is the enemy of a home.)

1. With the 4" hole drilled FROM THE OUTSIDE, slide the vent in the hole to mark the screw holes.

2. After marking the screw holes take out the vent and drill the screw holes with the appropriate bit for your screw anchors.

3. Install the anchors for the screws.

4. Use metal duct tape to tape the OUTSIDE seam of the steel vent pipe which runs along the length of the vent pipe to the flapper end. Taping the outside will prevent a problem with a clogged vent if the tape comes loose in the future.

5. Put a generous amount of silicon caulking around the back, flat side of the vent before sliding it in a final time. Do not put too much close to the edge to prevent caulk from squeezing out when the unit is screwed tight. (Caulking the back helps seal the unit tight against the wall after screwing it in. The included screws appear stainless, but can always be changed out if they rust in the future.)

6. Screw the unit in place, being careful to not overtighten which can loosen anchors.

7. Use 100% silicon caulking on the top and sides of the unit, but not across the bottom. This way, if any water gets behind the unit in the future it can exit the bottom.

8. Celebrate your vent installation with the beverage of your choice!