cabin filter for a 1998 e-300 turbo diesel

it is my understanding that there is some sort of air filter that filters the air comming into the cabin of the car does anybody know about this? is so where would i find it ? and how would i go about replaceing it ?
thanks

[JCE]

Detailed instructions are available from the Bosch site at http://www.bosch.de/aa/en/produkte/filter/innenraum/einbauorte.htm . Explanation of the instructions is on this page, click on your make to the right (MB) and after the Adobe acrobat page comes up, move down to your model. It looks like the filters are behind the glove compartment liner.

The filers are sold through Fastlane at a really decent price, compared to many other sources I checked.