When you're in the middle of a run, cushioning has to go the distance. The Nike Spark socks deliver on that promise, with optimal, breathable support designed for training. The thickness of the cushioning under the foot varies according to the target zones. The arch support is designed to allow you to wear the sock on any foot. Use it to adjust to the location of the underfoot cushioning. Fabric in the heel provides excellent foot support. Mesh on the top of the foot for ventilation.