Massage balls have a long history in Chinese culture, they originated in the Chinese city of Baoding during the Ming Dynasty and are still used to this day. Chinese Healthy Balls stimulate and exercise your hands muscles by moving both of them in one hand. Play them to relax and reduce stress. Made of beautiful blue corundum marble stone. Each ball is about 1.50" in diameter. Additional Details ------------------------------ Product description: Massage balls have a long history in Chinese culture, they originated in the Chinese city of Baoding during the Ming Dynasty and are still used to this day. Chinese Healthy Balls stimulate and exercise your hands muscles by moving both of them in one hand. Play them to relax and reduce stress. Made of beautiful blue corundum marble stone. Each ball is about 1.50" in diameter.