Baoding Chi-Gung Hand Exercise balls are widely used to develop strong and nimble hands. They are said to stimulate chi energy flow through the hands and fingers, and to promote heath, and maybe even stave off arthritis. They’re also great as a warmup before any activity that requires a lot of manual dexterity. These balls are made of steel with a stainless finish, and have musical sounding plates inside for a pleasant relaxing sound as they are used. Comes in a gift box. Approximately 2″ diameter.