Fitness balls are generally made of PVC materials harmless to human body, with a diameter of 65~75 cm. They are empty inside and need to be inflated. The standard diameter of fitness balls is 75 cm, and there are also 65 cm. According to the height selection, the standard ball is selected for those with height 1.60m or more, and 65cm is selected for those with height 1.60m or less. When using the ball, you can hold it with your hands and use your feet to clamp it, which is the best choice. The bearing capacity of the ball is 100 kg, and it feels very elastic, soft and comfortable when pressed by hand, indicating that the quality is qualified.