This zorb ball is used 0.9T 1000D/PVC or 1.0mm transparent PVC as material,adopt TPU to stick the lap joint .It is inflated with air and the air pleasure make it hold it’s shape .What’s more ,it has two skins ,the area between them is inflated ,and the 1.8 meter inner chamber is always open to outside .So you have fresh air coming in all the time.