I recently changed the oil & filter in my 2003 VW Jetta TDI, and wanted to post the pics of the cartridge filter. This is my first try at adding pictures to a post, so here goes. The first picture below shows a new filter next to the used one. The end caps of this filter appear to be a synthetic fiberboard of some sort. The new end cap below may look like felt, but it is stiffer and more rigid than "cardboard". Notice how much larger the center hole in the used filter is. The filter installs on a holder that passes through the end caps and creates an interference fit by folding the inner diameter of the end cap through hole inward. This interference fit must be oil tight or else the filter will bypass. There is no other gasket or seal in this area. Seems like a potential weakness in this design, but I'm sure it works. The image below shows the seam in the filter. The dots are small beads of adhesive, not metal clips. I sawed the top cap off by cutting through the filter element. The filter element itself was very stiff. The paper appears to be some sort of heavy cellulose paper. The plastic center core was not glued to either the top or bottom end cap. You can see how the element sprung open when the top end cap was removed. The center core is plastic. Very rigid. I know there is concern on this board about the possibility of ecores imploding, but after inspecting this one I don't think that is a concern here. One more view below of the core, filter element and the top end cap removed. I did not count the pleats or accurately measure the element, but I did stretch it out to just over 6 feet.