This is a nice little pin fire "Deringer" and was manufactured in Eibar, Spain. The second barrel is fired by pulling the hammer to half cock and then rotating the barrels one-hundred and eighty degrees with your off hand, then cock the hammer and pull the trigger. Loading was accomplished by pulling the hammer to half-cock and the rotating the barrels ninety degrees, remove the spent cartridges and inserting new ones, being sure to get the protruding pin in the slot in the barrel. Age is hard to figure, it could be as early as the Civil War, when pin-fires came out, however they were activly used in Central and South America until 1920 or so. This one as you can see is nickel plated with a nice patina and has checkered wood grips.