DuraBall PRO Professional Exercise Ball - Yellow (18 in.);

Fitter First FBPC45 Duraball Pro Exercise Ball - 45cm(Yellow) The World's Strongest Exercise Ball The Duraball® Pro is the strongest, safest and most burst resistant exercise ball available. The Duraball® is the best choice for advanced users as it offers the maximum firmness and support and is perfect for training. It also works great as a chair when under inflated.