The S4 is a game-changing innovation in fitness training for swimmers, surfers, and people looking to strengthen their shoulders.
- You exercise in a natural range-of-motion not constricted by weights, cables, pulleys, stretch bands, or a machine.
- You access levels of resistance from minimum to maximum that you control without having to interrupt your workout
- You gain strength and stamina thanks to the science of granular resistance.
Your S4 comes with a 90-day satisfaction guaranteed warranty and a lifetime warranty on parts and labor.