QUOTE(malcolm2 @ Jun 4 2020, 05:43 PM)
I have never seen one, but I don't think they are paper.
They are. The are the same foil backed corrugated paper tube material that is used in the cowl just a larger size with a smaller one fit inside it & as George said FG packed into the void. The whole affair is then held together by plastic end caps glued on.
I have several FS. Same unit used in both 911 & 914.