Product review (1 stars): Lousy Quality! Lets Heat Out!
The flapper has warped after 4 months and now there is a 1/4" gap around half of the opening.  Cold air pouring in!  I suspect the plastic used to mold the round part warped from heat sucked out from the Jenn-Air gas cooktop.  Don't know what I am going to do but will never buy another "Jenn-Air?" wall cap.