Design: FlyKnit—AtomKnit Flyknit fabric is stretched, steamed and set, delivering a lightweight, contoured fit with minimal water absorption and enhanced breathability Shoelaces are notched so the laces stay in place In-Shoe Comfort: Nike ZoomX foam in the heel is incredibly responsive and lightweight, giving you optimal energy return and impact absorption for your miles Zoom Air unit, delivering efficient energy return with every step Durability & Traction: Carbon fiber plate provides a snappy sensation with each step Additional Details: Designed for 800m – 5000m events Removable spikes