Product Description:Newton Cradle Pendulum, Metal Perpetual Motion Toy & Swing Balance Collision Ball Decoration Figurine Package Contains: It has 1 Piece of Cradle Pendulum Material: Plastic, Iron Dimension: 11cm x 13.5cm x 13.5cm Weight: 400gm Additional Information: Based on the law of conservation of momentum and energy conservation, due to resistance reason, newton's cradle will not swing forever. Usually, when under normal circumstances, the balls will swing about 15 seconds. But because of different forces and environments, the swing time will be different. Noble Design: Note: Pendulum may tangle if you operate wrongly. Kindly handle with care while unpacking.