Supportive and comfortable, the Nike InfinityRN 4 is designed to return energy with every step, adding spring to your step and making the most out of every run. The ReactX foam adds bounce and cushioning, while the waffle outsole provides traction and grip. Cut from a flexible Flyknit upper and a water-resistant membrane that won't let the weather stop you. The padded foam collar makes for a comfortable wear and supports the foot with a snug fit.