very fun decompression toy that a ball can be used to hit other balls and swing. Not only demonstrates a pendulum, but also shows the conservation of momentum and energy. Made of steel, shiny, preservative and not easy to rust. As a creative decompression desk toy to bring fun to people. Perfect for decoration in the office, home and other indoor places. Can be a fun gift for your friends, family and children. Color: as shown Material: metal Package Contents: 1 x pendulum ball Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3 cm.