Baoding Balls were first made of solid iron and called "Iron Balls". These solid steel balls are the most similar to the traditional iron balls and are the heaviest kind of balls. Made of solid steel and protected by nickel plating. A 35 mm set weighs about 0.76 lb, a 40 mm set weighs about 1.2 lb., a 45 mm set weighs about 1.6 lbs., and a 50 mm set weighs about 2.3 lbs. Rotating these heavy balls will definitely give your hand a workout.
Also known as Chinese exercise balls and Chinese health balls.