U-boat cloth, metal thread

[AlikN]

Here is a cloth U-boat badge, I would like to get some opinions on it.
Left side of the badge has some green oxidation to the metal thread,
another thing I noticed that cloth is blue on obverse and dark blue almost black on reverse.
Can anyone post their cloth metal threaded badges.

Thanks
Alik

[AlikN]

2

[AlikN]

...Anyone......... .