The Topo Athletic Ultrafly 6 is a light-stability road shoe engineered for high-cushion, smooth daily miles. The redesigned medial post wraps the heel for guided stability throughout the gait cycle, while the evolved ZipFoam midsole delivers a softer, more responsive ride than its predecessor. Additional rubber outsole coverage improves durability and traction, and the anatomical roomy toe box lets toes splay naturally. 5mm drop, 32mm/27mm stack, 9.6 oz (M9). APMA Seal of Acceptance.