spyguy said:the felt strip is placed inside the door to protect the window tint from being scratched when you open and close the window.
This is the first car i tinted, so i wanted to do it right. i learned about this felt strip from another forum. i ultimately didn't get a felt strip in the door, cause the guy who installed mine said it wasnt necessary. I dont trust him, however, i have had no scratches whatsoever from opening and closing the window with tints on.