"Link Era" Tension rod washers.

[Jules]

These had the same outer diameter as the rod heads (or extremely close to it), and you don't see them up for sale very often. But they were always something that sold easily and quickly years ago. I would guess that Sonor stamped these in house, but I couldn't say that with certainty. Does anyone know for sure?

[DaveInNZ]

I highly doubt they'd have bought equipment to make their own washers when German industry would have been rife with people that could make them, but I'd love to find something now that worked. They're by no means normal off-the-shelf items these days, especially in a country where metric is default.