Baoding Chi-Gung Hand Exercise balls have been widely used by Chinese as a way to keep the hands nimble and balance energy. Taoist and Chinese medicine believes using the balls to exercise the hands stimulates the meridians (energy channels) connected to the hands, promoting health, and preventing arthritis and rheumatism. Baoding Chi-Gung Balls are a great way to warm-up for activity that requires manual dexterity. Each ball size approx: 1.75" in diameter