Cushioning: Exceptionally High Support: Robust Responsiveness: Balanced Key Upgrades: ReactX Foam, Updated Flyknit, Enhanced Toe Box The Infinity RN 4, with its supportive cushioning, ensures a smooth running experience. Crafted with soft, comfortable Nike ReactX foam and featuring Nike Running's latest, most comfortable Flyknit, this road runner lets you start anytime, anywhere. Its high-rise foam stacks and intuitive design support each stride, providing peace of mind to run faster and farther. The fit is snug, so consider ordering a half-size up.