BOJIN Classic Newtons Cradle Balance Balls - Plus Size - Metal String - Black We have showed 4 types of ball collision as a reference. It has more than 10 types of impact combination.Players can enjoy the creativity and experience the fun of physics. Please do not pull-up to a too high degree ,45will be proper. Because the higher the position of the swing ball be pull-up, the greater the impact force to the stationary balls ,and it may lead to tangle up. 3.5 x 3 x 3.5 inches (this) 5.3 x 4.5 x 5.3 inches , 7.1 x 4.7 x 7.1 inches , 7.1 x 5.9 x 7.3 inches, 6.9 x 6.7 x 9.1 inches When you received the item,please take the balls out one by oneor the balls may be tangle up. It is suggested be placing horizontally.