I believe these were used on WW 1 helmets to hold the chin strap. I am uncertain whether the Nazis also did this. If you know, and want them, they are near mint condition. I have 4 of them - and they are $5 EACH. What makes these different from most Nazi bulleyes, which went inside a wreath on the front, is these have a loop in the back to accommodate the chin strap. CLICK THE IMAGES TO SEE THEM BETTER.