\If we use it the purpose of it is to keep foreign objects out of the gap
that's what I figured, i've seen some people use fiberglass insulation instead of polyfill inside their sealed boxes, that shit got everywhere on the subs, especially on the mesh on the basket (VVX 12's)
people are known to also not clean out all the mdf dust from there boxes when there finished building them and it get sucked into the motors
i'm guilty of that, had to shave the cutout for my new subs, forgot to clean it, got a face full of mdf dust when the first low note kicked in, scared the shit out of me, I had just finished putting vinyl cleaner on my dash so everything got stuck