"Boleadoras", are used by argentinian gauchos, (farmers), or "cowboys", to catch cattle; they spin them in the air, throw the balls wrapped in leather around the legs of the prey, and the animal, falls on the ground and they pick the cattle up, place it on their saddle to take it home and have a feast or "ASADO".
I took this picture in Areco Argentina, at the Silversmith Museum of San Antonio de Areco is in the Province of Buenos Aires, Argentina.