It is made of either rubber or synthetic material (pliable plastic) provided it possesses the same elasticity as rubber. It is from 18 to 20 cm in diameter and must have a minimum weight of 400g. The ball can be of any colour and should rest in the gymnasts hand, not the wrist. Fundamental elements of a ball routine include throwing, bouncing, and rolling. The gymnast must use both hands and work on the whole floor area while showing continuous flowing movement. The ball is to emphasize the gymnasts flowing lines and body difficulty.