Steeda now ships it out with 2 tubes. Late Model Mustang knows about the rear window moldings. Over some time the moldings will eventually start to corrode and rot. If you've got a Mustang and like to keep it looking sharp, aged window moldings do not do to much to help the appearance. Over the years people have come up with different methods of cleaning up and beautifying the moldings.
None are permanent.
You could go out and buy some new rear windows, which we all know is very expensive. The moldings are fixed permanently to the glass. I have heard some talk about a method of removing the old moldings from the glass and replacing them with new ones. This is very costly, negating the feasibility of ever doing it. So most of us do what we can to help, some just let it go, giving up hope of a simple solution.