KRight&reg; Concise Paragraph Newton's Cradle Ball Billiards Full Metal Bracket (13*13*17cm) Newton's Cradle makes a great desktop gift. Educational toys that help children learn Newton's Cradle is a clever device that not only demonstrates a pendulum, but also shows the Laws of Conservation of Momentum and Energy. Material: iron frame + steel ball + ABS base These swinging balls will keep you occupied for hours at work.