Description: It shows the principles of Conservation of Energy. What's more, it can also help children experience the fun of mechanics in the process of playing and stimulate children's learning fun. The sturdy wooden base can keep the smooth operation of the cradle balancing balls. You can explain to your child the physical knowledge and stories with this product. Made of metal and wood materials, which is durable to use. The length of the small one is 14cm, the width is 13cm, and the height is 11cm. The length of the large one is 18cm, the width is 18cm, and the height is 12cm. The pendulum balls is a perfect decoration for desks and tables, whether at the office, classroom or at home. Item Name: Newtons Pendulum Balls Material:Metal,Wood Size: S: 14cmx13cmx11cm/5.51inx5.12inx4.33in L: 18cmx18cmx12cm/7.09inx7.09inx4.72in Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 1 X Newtons Pendulum Balls