Factory provide gym ball directly. You will not only get good quality poducts,but also get information of process during. Fitness item: gym ballMaterial: quality PVC (ATBC/DOP)Diameter: 18" ,20" ,21",22",25",28",32"an so onweight: 600g till 1400g per pieceAccessory: pump, measuring tape, wall chart, plug Various colors are available Massages user while exercising