I have these central ac vents they are square and 11 1/2 inches X 11 1/2 X 1 and I am trying to stop the draft which is coming from them they are ceiling mounted. They have a damper which can be opened or closed by turning a screw in the center but it does not stop the cold air from coming in completely. Forgot to mention they are plastic. Anyone have something like these or similiar, any ideas on how to cover them. Dont want to use duct tape and plastic ! I was hoping I could find a product that would snap on like a tupper ware cover . Home depot nor Lowes has anything that would work.