Vintage Watch Chain

This chain belonged to my father, possibly my grandfather. My father was a very pragmatic man. Everything had to have a purpose. Nothing was just for decoration. A few years ago, my mother checked his old toolbox. In the box she found this chain. I believe it was meant for a watch. My father probably kept it because he could envision utilizing it for some practical use. That was my luck because otherwise he would have tossed it out.
The chain is nothing special. It is gradually getting bigger/smaller depending how you look at it. It is marked “double” – meaning it is NOT gold.

Thanks for looking:)