We've taken one of our best-selling 60cm (24") therapy balls, filled it with some smaller PVC balls, and weighed it down just a bit. Contains 1400 grams (3 pounds) of sand. The overall benefits is that it won't roll away when you finish using it. The Stay N Place Ball is great for traditional balance therapy, as a chair, or for encouraging proprioceptive responses when lifted or passed around. It has the same great feel as an ordinary therapy ball with the added benefit of weight. Color may vary. Latex free.