The S1 is our take on the everyday road trainer, engineered to meet the mileage demands of ultrarunners. Designed to excel on the longest training runs, it has been proven in training and competition the world over. With all the comfort and longevity you need, the S1 supports you through every step.ZeroSag midsole insert with little degradation during long runsLightCELL midsole base featuring excellent lightness and bounceGOFLOW midsole geometry to guide your strideOutstanding stability for your long-distance trainingBreathable and eco-friendly