Our newton cradle use nylon line of good material instead of cheap fishing line which other sellers used. Wooden base and the unique design idea make an impression. Different size give you more choices. The balance balls continue in perpetual motion for only 15-25 seconds due to the resistance of the air and friction, but it won't influence the effect of playing although it can not reach the seamless convergence among balls in the vacuum.
Brand new and high quality.
Not only demonstrates a pendulum but also shows the Laws of Conservation of Momentum and Energy.