Features:Brand new and high quality.Not only demonstrates a pendulum， but also shows the Laws of Conservation of Momentum and Energy.Friction and damping effects are also observed.Often used as a toy to amuse people.Includes steel balls， plastic frames and base.Great gift for everyone.Size:18cm x 11cm x 14cm - 7.09inch x 4.33inch x 5.51inch.Package Included:1 x Balance Balls Desk Toy