The article is in the Jan Feb issue of the star, and there are Three filters. The charcoal should be changed every 75K or four years, the dust filters every 45 or two years. I guess you need a vacum source to collapse the seal in order to get this filter out. The article claims the filters are $500 and it took 3hrs to remove the wiper assy and change the one filter. I shure hope some one can scan the article for you it shows it in good detail. I did go to the MBstar and it is not available on line!