The ball is made of PE plastic, which is durable. This product does not need to be installed and can be used directly. If you throw the ball out, the ball will of course become bigger. If the ball falls to the ground or hits an object, it will automatically shrink and become smaller. This kind of fun is endless. Name: Colorful luminous magic ball can be enlarged and reduced Material: PE, and tasteless Size: Unstretched diameter about 7inches After stretching, it is about 12.6 inches directly Notice: Due to manual measurement, there may be slight errors in the size of the product. The color of the product may have chromatic aberration due to lighting and photography. List: Luminous telescopic ball1