For what it's worth.....
 

don't shoot the messenger:

http://www.ebay.de/itm/Fangschnur-fu...item23353a2966

Looks like the round leather drive belt from a treadle sewing machine (like a Singer) to me...

Actually thought exactly the same thing, that belt brought me back to my childhood, it reminded me of the old sewing machine my mother had when I was little.

My mom had one too. It was way cool!!! I used to play with it on rainy days...You flipped up the table-top and the sewing machine unfolded up from underneath...Black enamel with gold lettering, all kinds of bobbins & pulleys...And the skeletonized iron treadle had 'Singer' spelled out in script in the middle...Big handwheel on the left side to get it started... :D

This is a lanyard for a Lahti pistol. They are quite common. I have a milk crate full of them. There is no provision for attachment like the much more rare P-08 lanyard.