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. Features: Pull back one or more balance balls and release them, the same number of balls will swing up on the other side. This desktop toy provides you with many entertainments, suitable for various places such as home or office. When you are tired of learning and working, you can put it on your desk, a cool and nice desk ornament for office. Excellent educational scientific tool not only shows the pendulum, but also shows the law of conservation of momentum and energy. Suitable for home decoration, study or office table and chair decoration accessories. Also suitable for birthday gift and children's toy. Specification: Condition: 100% Brand New Material: ABS Plastic, Tough Fish Line, Solid Metal Ball Size: S, M, L (optional) S Size: Base Size: Approx. 7.3 x 8.8 cm / 2.9 x 3.5 in Height with Base: Approx. 9.4cm / 3.7in Frame Size: Approx. 8 x 7 cm / 3.2 x 2.8 in M Size: Approx. 14 x 11.5 x 14.5 cm / 5.5 x 4.5 x 5.7 in L Size: Approx. 17.5 x 14.7 x 18 cm / 6.9 x 5.8 x 7.1 in Ball Size: Approx. 2cm / 0.8in Base Height: Approx. 2cm / 0.8in Weight: Approx. 94g-404g / 3.3 oz-14.3 oz Package List: 1 x Pendulum Ball Toy Note: 1. Please allow 0-1 inch error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.