Is it really necessary? Mb supposedly have no idea though they are able to supply a complete replacement air filter box is £230 + vat, my oh said no chance so I had to posh it up and make do. The original foam has crumbled away.
Yes it is necessersary. I means that air is only admitted via the filter assembly throught the air intake in a controlled way.MB would have no idea as they would have had the part made as awhole by a third party supplier.
As long as you get a good fit any foam seal should work as above.