The first person to break the 2-hour barrier for a full marathon was wearing a prototype of the Nike Air Zoom Alphafly Next %. This Flyknit version adds comfort and flexibility to the upper, while responsive foam and a pair of Zoom Air units combine to push your run forward. Nike ZoomX foam is responsive and lightweight for optimal energy return. Two slim, visible Zoom Air units deliver the most energy return of Nike's racing shoes. Full-length carbon fiber plate gives you a snappy sensation with each step. AtomKnit is Flyknit fabric that's steamed and stretched for a lightweight, contoured fit. Outsole was created using data from hundreds of runners. Data-informed design features different angles of traction where you need it. Cushioning helps make each step feels soft and plush, keeping you comfortable through the later miles of your race. Integrated tongue provides a consistent fit with comfortable lace-up.