Description:This device demonstrates demonstrates conservation of momentum and energy via a series of swinging balls. When one on the end is lifted and released, the resulting force travels through the line and pushes the last one upward; or pushes one side, all balls will swing together in a line. Swing one, two or three end balls and the changing colors will keep you entranced for hours with multiple color changing modes from blinking to cascading. You can put it on your office desk or your home desk or on your shelf. It will be cool desk toy. Features:These glass balls are environmentally friendly, non-toxic and are designed to last for a long time.Excellent educational science gadget. Not only demonstrates a pendulum, but also shows the laws of conservation of momentum and energy.Science toy. When feeling tired of studying and working, you can stir balls to hear the clinking sound to ease.Install batteries, it will light up on the base board, and the balls will look colorful and beautiful, very attractive.Great for home ornament, study or office desk table decor accessories, etc. Also good for birthday gift and kids toy.Specification: Condition: 100% brand newMaterial: Glass + fishing line + plastic baseColor: As pictures shown Battery: 4 x AA batteries(not included)Size: approx. 12 x 9 x 12cm / 4.72 x 3.54 x 4.72inchPackage Weight: approx. 185gPackage 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..3. Please note that the color of the base will be sent randomly, and make sure you will not mind before ordering.