AN OLD ORIGINAL BLACK POWDER LEATHER ADJUSTABLE SHOULDER SLING FOR MUZZLE LOADING RIFLES. 
IT'S MARKED IN UNITS ON THE SIDE OF THE SPOUT (BRASS?) AND THAT'S A 15" RULER,, ABOUT THE POUCH SIZE WITH A LARGE ADJUSTABLE SHOULDER STRAP. LIKELY 1800S AND STILL SUPPLE/FLEXIBLE. THE LEVER SPRING IS STILL STRONG AND THERE IS A BULLSEYE PATTERN ON THE PUSH KNOB, OTHERWISE NO MAKER MARKS/DATES I SEE AND HAND MADE IS MY GUESS ANYWAY.
ASK FIRST PLS, INCREASE OF EBAY IGNORANT BUYERS, BY BIDDING YOU AGREE WITH DESCRIPTION
Please check my feedback as I work hard for it and I pack very well to try to foil the USPS short comings, so please check 5's and bid with confidence as I have great feedback and ship very quickly and am a Collector, just as you and I tried as best as possible to describe this to you as I see it and that's with a Collectors eye not a Sales mans !!! Thanks. I've been a Collector for  OVER 50 years and have most of my things from when I was a kid and may list anything from Military to Bohemian Engraved and Cut glass, Pottery and Unique items. Enjoy your treasure hunt and call with questions 860 455 5480 is my cell.