The BOSU® Surge® is a cutting-edge hydro-training device that uses water to provide an unstable load. Strategically placed angles allow the water to crash and shift, forcing your muscles to react to constantly shifting water – creating top-down instability. The Surge® provides a unique challenge to the joints and stabilizing muscles by forcing the body to resist and control the unpredictable nature of the shifting water. Three different grip options give the Surge® the versatility demanded in today's training. From farmer's carries to overhead lunges, the Surge® will help you achieve and exceed your fitness goals by training your body to react to real life movements. The Surge® 60 ranges from 10-60 lbs. when filled with water.