Product review (5 stars): KEEP THE CRITTERS OUT!!!
Easy to install.  Love that it has the double flap to keep the critters out.  We've replaced our vent hood twice since our house was built (1998).  I know that sounds like a long time, but the last one was replaced about 4 years ago.  It was one of those with the 4 vent flaps that open.  Don't get one of those.  The vents break and they also had lint build up on them, which kept them partially open and a field mouse ended up getting into my house.  This one seems to be built much sturdier and the plastic is MUCH thicker than those other styles.