Feature: 1. MAIN PURPOSE: This balance pendulum ball is a great table decoration, it can not only add beauty to the room, but also relieve your study and work stress. 2. WORKING PRINCIPLE: Pull the ball on the left first and then let it go, the ball on the right will stop after collision. If you pull the 2 balls on the left at the same time, they will stop after the collision, and the 2 balls on the right will swing. 3. PENDULUM EFFECT: 5 balls are placed side by side, touching each other and the centers of the balls are in the same line, and the swing distance is roughly the same as the distance the balls are pulled apart. 4. EDUCATIONAL TOY: As the perfect educational toy, it guides children to understand the meaning of energy conservation and allows children to learn scientific principles while playing. 5. DURABLE MATERIAL: The balance pendulum ball and base are made of excellent materials, beautiful and durable, and can be used as desktop or coffee table decoration. Specification: Item Type: Balance Pendulum Ball Material: Iron, Birch Wood​ Assembled Size: Approx. 14 x 13.5 x 11.5cm / 5.5 x 5.3 x 4.5in. Package List: 1 x Base1 x Balance Ball Note: 1. Manual measurement may have 0‑1cm error. Make sure you do will mind before ordering.2. Due to the difference of different monitors, the picture may not reflect the actual color of the item. Thanks!