Flat thing

[AngusAardvark]

I presume that this is part of a larger object but that's as far as I get. The ring rotates.



and the other side


detail on the markings

[dognose]

Hi,

It's a watch key, it would be connected to a watch chain. If you look at your first image, you will see the outside engraving resembles a watch face.

Trev.

[AngusAardvark]

Thanks Trev

Asking Google for images of "watch key' produces many similar things. Hard to see how effective it would be since the bit that presumably goes into the watch is a completely round tube but it must have worked. A square or triangular fitting might have wound better.

[dognose]

This is likely the very reason why it is no longer with the watch. It would have been square originally, but rounded off over a period of time and thus become useless and a replacement required.

Trev.