ScienceGeek Newton's Cradle Desktop Gadget 3 LED Colors Change Shine Light Ball Balance Ball The Newton's Cradle Light changes colour as it swings. There are three colors of the balls when it is working. You can press the button on the left to change the colors. You can put it on your office desk or your home desk or on your shelf. It will be cool desk toy Performing based on Newton's Laws Power: 6 x AA Batteries (Not included)