Meet the C1: where serious distance meets serious fun. Our dual-layer midsole pairs eco-friendly CircleCELL foam with a supportive rubberized EVA base for performance that doesn't compromise on sustainability. The TUNEDFIT Dual Lacing System lets you customize fit separately for forefoot and midfoot—perfect when your feet swell during those epic ultrarunning days. A wider base and higher sidewalls keep you stable mile after mile, while weighing just 9.4 oz at a 42 mm stack height with 6 mm drop. Built for the grind. Trusted by record breakers like Matthieu Bonne, who relies on the C1 for his 100 km training days and beyond.