Product review (4 stars): I used the existing tube that went through the wall ...
I used the existing tube that went through the wall when I installed vent cover.  It seems a little light, but it might need to be that way to open when the dryer is on.  I had mice coming in through the old vent and so far it seems to be keeping them out.  I had to use my own masonry screws, package didn't come with them.  I gave it 4 stars because the package should have come with screws.