Newton's Cradle Kit - Physics Balance Balls - 7 inch by 5 inch Science Display - Executive Office Newton's Pendulum with 5 Metal Balls Newtons Cradle Balance Balls on 7" stand, sits 5" tall Newton's Cradle makes a fantastic & affordable desktop gift The kinetic energy will mesmerize and inspire you while at work! Newton's Cradle not only demonstrates a pendulum, but also shows the Laws of Conservation of Momentum and Energy Stands 5" tall on a black base. Balls are made of metal while stand is plastic.