Some insignia of the submarines are extremely rare, while others are common. In the wearing photo, we see a submarine staff member with a qualification badge. Apparently, this badge was only given to the crew serving on the ships, so it is extremely rare. Compared to this, there are quite a few copies in online auctions, where the more honest sellers do not forget to note that their item is not a contemporary piece.
That is why I chose one of the more common patriotic badges for the nice wearing photo. The most common central element of these is the stylized model of the U 5 ship, which was then supplemented with a wide variety of colorful frames. One of these is the rectangular frame shown here with German and Hungarian national colors, which is relatively less common compared to the simpler round frames.