CULER Newton Cradle Steel Balance Ball Physics Science Pendulum Desk Fun Toy - Home Decoration Material: Solid steel ball, nylon plumb line, ABS plastic frames and base strict QC standards. Ship By USPS 5-8 Days Arrive. It is a best and useful gift for children to arouse his or her interest in physics. When you are sleepless, just move your eyes with the bump of the ball, then you may slowly, slowly falling asleep. ull up one ball and release,only one ball in the other side moves,pull up two, two balls will react, and so on. Suitable for the place such as office, desk table,computer table etc.