18 inches when fully inflated, yellow. Exercise balls are used to improve balance, coordination, flexibility, strength and even just for fun. Balls are used as aids for vestibular movement and equilibrium therapy, by fitness professionals as an aid for stretching and strength programs, as seats, and even by pregnant women in birthing classes. The Cando balls have a non-slip PVC vinyl surface that is ribbed for extra security. The balls may be "under" inflated to give a soft, mushy feel or "over" inflated for a firm, bouncy feel. Balls can support up to 300 pounds (136 kg) and come boxed. There is no actual image of this item. The image shown is representative only. The actual item will be yellow.