Part number is 108R01037
And it is totally optional.
I have a Phaser 7800 printer and i see on the left side that it have a slot, named R10, that seems to be able to contain a filter.Here some photos:
There is some OEM xerox filter for this slot? i haven't find anything by google searching ...
Or it can be used to insert a aftermarket "particulate filter" ?
Thanks a lot for help!