Mystery German Rifle Sling.

[The Arctic Fox]

I just got a sling off a friend that is brown leather, about 52 inches long, steel buckle at one end and steel stud at other.Also typical 3 parallel stitched a one end. It has stamped what looks like an eagle of German WWI era over possibly HNL2 code. Also stamped, most I can make out, factory done KRIECRBECKER&CO. KG over BERLINSW08 over a hand stamped 57. I may have the 1st few letters misread.
So what kind of sling did I just obtain for my collection? Thanks................(Answer below.)

[The Arctic Fox]

Any educated guesses? Might be early droop wing TR.
Or perhaps something other than rifle sling?

[The Arctic Fox]

Okay. It is an early German KKM Trainer Sling. Buckle slide and 1 hole at end. Somewhat rare.
A friend has a few various .22 Mauser Trainers. This sling can be found on the net.