Jacob Rupertus, .22 rimfire cal. single shot derringer.  Serial #NSN.  Good condition.  Relatively rare derringer from the late 1800s with reportedly only 500 or so made.  3" round and octagon barrel has some rifling, but has corrosion, fixed sights.  The barrel twists to the left to open.  70% nickel finish with wear and some light hits.  Appears functional.  Dark smooth wood grips are in very good shape.  Antique so it can ship directly to you where permitted.