Product review (5 stars): No more ice buildup.
Works perfectly.  Our freezer was all iced up and would not defrost due to the original duck valve used.  After installing this and removing all the ice, used a hair dryer on low, no more problems.

Check with the other review to see if they will pay for the part.

Google some youtube videos on how to install this.  There are a few out there and they tell you how to do it.