Newtons Cradle Steel Balance Ball Physics Science Pendulum Early Development Educational Desktop Toy Gift Office DecorationNewtons Cradle Pendulum Balance Ball Perpetual Motion Physics Decor GiftProduct Features 1. Strong Line: Our newton cradle use a high quality nylon line that is strong enough to not be broken easily. 2. Black Wooden Base: The hard wooden base can keep the smooth operation of the newton's cradle balance balls. 3. Swing Time: 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