It is a very funny decompression toy that a ball can be used to hit other balls and swing. Not only demonstrates a pendulum, but also shows the Laws about conservation of Momentum and Energy. Made of steel material, bright, preservative and not easy to rusty. Perfect for decorating in the office, home and other indoor places. Can be a funny gift to your friends, family and children. Features: It is a very funny decompression toy that a ball can be used to hit other balls and swing. Not only demonstrates a pendulum, but also shows the Laws about conservation of Momentum and Energy. Made of steel material, bright, preservative and not easy to rusty. As a creative decompression desk toy to amuse people. Perfect for decorating in the office, home and other indoor places. Can be a funny gift to your friends, family and children. Specification: Condiiton: 100% Brand New Color: Sliver Material: ABS + Steel Ball Diameter: 1cm / 0.39"(appr.) Ball quantity: 5 Small Balls Packing: Carton Size: (L) x (W) x(H) 8.5 x 7 x 9cm / 3.35" x 2.76" x 3.54" (appr.) Package Included: 1 x Balance Balls Toy Notice: Please allow 1-3cm error due to manual measurement and make sure you do not mind before ordering. Please understand that colors may exist chromatic aberration as the different placement of pictures.