Feature: 1. An excellent educational science tool shows the swing, but also the law of conservation of momentum and energy.2. When you are tired of studying and working, you can stir the ball to hear the jingling sound to reduce stress. 3. Owning scientific history and exploring the important value of physics, suitable for birthday gift and children's toy. 4. Pull one or more balls backwards, release them, and the same number of balls will swing on the other side. 5. Interesting and suitable for decoration, perfect for home decoration, study or office table decoration accessories. Specification: Condition: 100% Brand New Item Type: Home Ornament Material: Metal Product Size: Approx. 8 x 7 x 9 cm / 3.1 x 2.8 x 3.5 in Package List: 1 x Ball Toy |