Description: Pendulum ball so some simple assembly work is needed before using it. After you have it you will play it with a great sense of accomplishment. How to Use:To make the glass balls move just push it slowly with the supplied strip then gently loosen it. Desk Office Decoration: Show some character and express your science and physics with this decorating your office space. Educational Toy: Use this in class and share with your friends and family the exciting physics and science. Quality Materials: made of durable and metal also good for birthday gift and toy . Specification: Material: Metal Color: Black Size Chart: 13.5cmx11.5cmx13.5cm/5.31inchx4.53inchx5.31inch Package Includes: 1Metal cradle Balance Ball Note: Please allow slightly errors due to manual measurement and different monitors.