Boxing Ball Bladder Specifications: A professional-style speed bag that is fun for all ages and is great for the home or office. The strong suction cup base sticks to most smooth surfaces . Boxing Ball Bladder 1) New style 2) Make use of high-quality natural rubber and butyl rubber 3) 2 layers rubber teguments annexed to keep balls airtight 4) Balanced technology 5) Material: natural rubber and 30%, 50%, 70% butyl rubber.