To me this looks like a good, honest been there and done that WW2 sling. It shares all the characteristics of my MG42(34) sling, specifically, focusing on the forward snap hook (2nd pattern). I would say that this sling will have a Waffenamt, or nothing at all, on the rear pistol grip fitting, just like mine. The leather will probably be marked in a similar fashion to mine i.e. large Waffenamt, maker code and year.
All wear and tear, i.e. rounded off corners, dirtying of leather etc etc all seem perfectly authentic and in keeping with use. In particular the leather at the pistol grip always gets battered as it sits in the dirt.
One half decent way to ascertain if it is a genuine, used sling is to enquire whether one strap is longer than the other. Reason being, is that when the weapon is being shouldered the outer strap has to stretch to accomodate the extra distance it has to traverse over your shoulder. See my photo below.
The finish of the metal work appears to be the same as mine i.e. black enamel paint.
The only significant difference to mine is that the front, snap hook D-ring is slightly wider than the one on mine, giving a bit more left and right rattle for the leather.
Anyway, I've tried to replicate the original photos so you can compare my sling to that being offered.
PLEASE 'RIGHT CLICK' AND OPEN IN A NEW TAB/WINDOW TO SEE THE FULL FRAME OF THE PHOTOS.
Also, here is a link to some measurements I did for another forum member so you could use that for your enquiries. Again, right click and open in a new tab/window for the full photos.viewtopic.php?f=25&t=12965&p=92995&hilit=sling#p92995
If it was me, and I was in the market for a sling, I would jump on this, looks honest and cheap.