SS and others sell it. The VB one is on par with their other stuff. The VB one seemed neat because it was a strip of felt with sticky already on the back. However, I found trying to get it into the channel close to impossible. I do not believe the original was glued in, but only attached at the top and bottom. However, I glued in my SS one along the outside edges only, being very careful to get the fabric all the way back and into the corners. I did not want the "cup" of the fabric to effectively narrow the size of the channel. If this does not make sense, let me know and I will go into more detail.
Jay