China's traditional hand sports equipment has a history of thousands of years. Very simple:put 2 or more iron balls in your hand. Hollow in the middle. Keep your hands,fingers,wrist,and arm . Recommended by hand therapists,using baoding balls can strengthen your hands and keep them flexible helping to manage hand conditions such as and damage. Many other benefits such as keeping your hands busy to stop bad habits,improve circulation,help with for and meditation,increased concentration,and more.