This device demonstrates the conservation of momentum and energy through a series of pendulum balls. Pull back one or more balance balls and release them, the same number of balls will swing up on the other side. It can well develop kids learning skills and hand-on ability. Features - Color: As Shown. - Material: Wood, plastic. - Size: About 14.50X10.00X11.00cm/ 5.70X3.93X4.32in. - Explain your child that physical knowledge and Newton's story, also help to explore the mysteries of the natural science. - Excellent educational science gadget. Not only demonstrates a pendulum, but also shows the laws of conservation of momentum and energy. - This toy is a perfect decoration for desks and tables, whether at the office, classroom or at home. - Pull back one or more balance balls and release them, the same number of balls will swing up on the other side. - Excellent educational scientific tool not only shows the pendulum, but also shows the law of conservation of momentum and energy. Package list: 1 x set of toy