DescriptionThis 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- Material: Iron + Plastic.- This Newton's cradle balance ball toy express your love for science and physics with this decorating your office space.- Pull one or more of the balls, release them and the same number of balls will swing on the other side. - When feeling tired of studying and working, you can stir balls to hear the clinking sound to ease. - Suit for both kids and adults, excellent for killing boring time and stress release. - Apply to psychology, teaching tools and furnishings. Frequency swing keeps you in a calm state.