Therapy balls originated in the Chinese city of Baoding during the Ming Dynasty (1368-1644 AD). According to traditional Chinese beliefs, the vital organs of the human body are all connected to the fingers. By manipulating these iron balls, it stimulates the circulation of blood and energy throughout the body. Our key chains are inspired by this tradition. 1.0" diameter x 3.5" long. Assorted color cases; please allow us to select for you.