Product review (5 stars): Great vent kit for a dryer or anything needing a ...
Great vent kit for a dryer or anything needing a 4" vent.  Has great backdraft dampers to prevent outside air from entering back into the duct.  The plastic louvers are solidly connected to the metal duct via tabs that fit into holes in the duct which is good, because it keeps the duct attached during installation.  I used this to vent heat out of a networking closet and coupled with a duct booster fan, it works great!  Well worth the money if you want a simple duct that looks good once installed, but functions well also.  It also has a square metal trim ring to dress up the inside and cover the hole through the wall, so that's great as well.