Product review (4 stars): Pipe is slightly too large but....
This vent works well. I had to buy it to replace the old one that would get clogged and jam open allowing chipmunks to enter and hide there from my cat.  It was very disconcerting to hear them running around inside my dryer hose and I feared they would move in and take up residence. The louvers are small enough to prevent those critters from entering.  My one complaint is that the pre-crimped sheet that rolls to form the vent pipe, once assembled was slightly too large and it took a great deal of finagling to get the vent to fit on the pipe. I had to create my own slight crimp in the metal to get it to work. For this I deducted one star.
The door itself (in which the louvers sit) does open up and can stay open for easy cleaning.