Features Strong Wire: Our Newton Cradle uses high quality nylon wire that is strong enough to not easily break. Black Wood Base: The hard wood base keeps the Newton's cradle balance ball running smoothly. Swing time: The balance ball lasts only 15-25 seconds due to air resistance and friction, but it cannot achieve seamless ion between the balls in a vacuum, but it does not affect the effect of playing. MORE DURABLE AND NO rust: Steel frame and 5 high polished smooth steel balance balls, more durable, easier to transfer and store more energy in the event of a crash. Suitable for: Suitable for psychology, teaching tools and furniture. The frequency swing puts you in a state of calm. SpecificationsType Countertop Metal Balance BallMedium 14*13.5*11.5 Small 9.2*9*7.5Ball diameter 1.0CMmaterial: metalbackground color blackSwing time 15-25 secondsPackage Included1 frame with 5 balls1 base