Newton's Cradle Steel Balance Balls Desk Physics Science Accessory Pendulum Desk Toy hots The item ship from china, it will take 8-18 business days arrive. the amazon estimated delivery time is later than the actual arrival time. Easy and convenient to use. Not only demonstrates a pendulum, but also shows the Laws of Conservation of Momentum and Energy. Friction and damping effects are also observed. Often used as a toy to amuse people. Color: Brown & Silver