Attached are some pictures of the finished seat back on one of my C8 seats.
Springs used:
https://www.fabory.com/en/helical-te.../p/17902160075
Rings used:
https://www.kleinmetaalshop.nl/ringe...20-x-3-mm.html
The rings are available from different vendors....they have a slightly larger overall diameter when compared to the original....(and the weld is a bit nicer than the original). Size 20x3mm
Alex