chain for pocket watch loop/ring

[Pyotr]

I have noticed over the years, many original trousers, (German army, air force)have either a small metal ring on the right hand side, under the trouser waistband, or sometimes a small loop (?) of fabric in the same place so that the pocket watch chain can be secured.
none of my repro trousers have this. so, my questions are:

1. Were trousers made without this loop/ring, or is this simple a cheaper way to make trousers, under the assumption no one uses a pocket watch any more?
2. The metal rings- anyone have a source, or / a closeup with measurements that would allow me to sew a ring on?

3. Did the ww2 trousers use small folded cloth loops as the first war German trousers did? Any one have measurements or / and a close up photo?

I often use a modern quartz watch in a pocket as it usually works, unlike my period watches, which may stop, and then I think I have hours to get up, only to find out I am late.

Peter