Sweat-wicking technology. The arch band contours around the foot for a secure fit and feel. Mesh at the top of the foot for light comfort. Reflective details for visibility during low-light runs. When you run, you want comfort that goes the distance. The Nike Spark socks deliver on that promise, with optimal, breathable support designed for training. The arch support allows you to wear your socks on any foot. Use it to adjust the location of the cushioning under the foot. Fabric in the heel for excellent foot support. Mesh on the top of the foot for ventilation.