This device demonstrates conservation of momentum and energy via a series of swinging balls. Pull back one or more of the balance balls, release them and the same number of balls will swing up on the opposite side.Features: 1.Science toy. When feeling tired of studying and working, you can stir balls to hear the clinking sound to ease. 2.Excellent educational & science gadget, own your very own piece of scientific history and explore significant values of physics. 3.Pull back one or more of the balance balls, release them and the same number of balls will swing up on the opposite side.4.Great for home ornament, study or office desk table decor accessories, etc. Also good for birthday gift and kids toy. 5.Z-shaped iron frame has a strong sense of three-dimensional6.The base is ABS plated with high glare7.The sphere is metallic, the touch will make a wonderful sound and will continue to moveSpecification:Condition: 100% brand newMaterial: Plastic + metalColor: Sliver Size:18.8*18*11.5cm/74.01*7.08*4.52inchWeight:506gPackage Included:1 x Balance Balls ToyNote:1. Please allow 1-2 cm error due to manual measurement and make sure you do not mind before ordering.2. Please understand that colors may exist chromatic aberration as the different placement of pictures.