EFS (Electrolyte Fuel System) is unlike any other endurance drink mix available. EFS combines the latest clinical research and nutritional technology with input from some of the best endurance athletes in the world. The result: a great-tasting energy drink that provides ALL the ingredients you need to maximize endurance during exercise. For example, each serving of EFS provides all five electrolytes (over 1,000mg/serving) in the levels endurance athletes need to stay hydrated, prevent cramping and maximize endurance. With EFS, you don’t need to carry extra electrolyte pills or bother adding anything to your energy drink anymore. Times have changed.