This is a ring made of piece of aluminium tube with screw thread, I suppose . It is one piece .
A shield with a cross, reminds me of Prussia/Preussen …….

...and the last one ......

a threaded AL tube! You could use a thread gage and test to see if SAE ]American threads ,,OR metric threads [rest of world!] if that would matter to you... but overall, a very cool piece!

Thank you for your reply Gaspare.

Probably the closest thing I have seen to "trench art"

Some guy with patience and a file could have made that.

Dave

You are right Dave. I think most of the soldiers were not very skilled but some of them were . It was a way to reduce the horrible war stress .