Newtons Cradle Balance Balls Science Physics Gadget | Desk Toys & Accessories Features： Material:Steel Weight: 100g Description： 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. Includes steel balls, plastic frames and base. Great gift for everyone. Size chart： Base size: 9cm*7.5cm*9.5cm, Ball diameter: 1cm Package included： 1 x Newton's Cradle Balance Balls Desk Toy Notes: 1. 1 inch = 2.54 cm 2. Please measure it yourself to choose the right size. 3. Due to the difference between the different displays, the picture may not reflect the actual color of the item. Thank you!