Gymnastik Balls are so incredibly effective for such a wide variety of exercises, that we believe no home gym should be without one. The Gymnastik balls are our best-sellers.These balls are made of thick molded vinyl, designed for active use in dance, exercise and therapy. Colorful and appealing to all ages, the ball is an indispensable aid in achieving normal movement and equilibrium. Regardless of your fitness level, the Gymnastik ball is a great exercise tool. This is the 120cm size ball.