Designed for feet that don't hurt. High-performance runners, cyclists, hikers and fitness walkers who prefer a minimal amount of foot protection. NOT Designed for: Active people with any distracting foot issues or long-time wearers of Thorlos thick or moderate cushioned products. Lightweight Achilles Tendon pad protects against rubbing and chafing while functioning as a heel lock. THOR?WICKCOOL fiber in the ball and heel pads provides enhanced moisture management. Specially sculpted THORLO pads in the ball and heel provide protection from shear and impact where needed. All but most of the essential padding, significantly reducing the weight of the sock. Ultra lightweight sock frame. Nylon covered LYCRA provides contoured aerodynamic glove-like fit. Mesh Polyester for maximum breathability.