...here is another solution (50 cents) to the fan box"
factory filter" and does not require any gluing since it's so stiff....just tim to fit.
I guess I could have purchased the $50 cover with the course filter from BMW, and hoped that it would last a few years - again, but found that a 50-cent Scotch Brite 9" x 6" pad trimmed down to 9" x 4.2", fits well (snug) into the cover without collapsing, but allowing no pressure difference (e.g no air flow restriction)...no more leaves, and more importantly, no more "jet engine" sound when the fan is on Max setting.