Product review (4 stars): Another Whirlpool Win!!!
What can I say?  It is a molded plastic wall vent cap.  Just as it was described on the webpage.  And yes it met all my expectations of channeling fumes from my stove inside the house to the outside.  And all this while preventing vermin from the exterior environment getting into the house.  Now that I think about it, it really is rather exciting!!!!