Spacer for Door Speakers???

[Makahveli]

I bought the FS80 component speakers from Boston Acoustics on a great deal, because it was slightly used. anyways it had this spacer that was about a half inch thick and was glued down to one of the subs. It look like it was part of the set, it surrounds the rim of the door sub but goes between the door of the rim of the sub. I wanted to know what is it and does it make a difference. I mean should I use it?

 

[M.Scott]

I used mine because without it the magnets hit the window track ( I actually added another 1/2" spacer) and the stock spacer was angled in the right direction and I wanted to keep that angle.