Size Chart The Progressive+ Socks activate the flow of blood in the muscles and stabilize joints, resulting in a reduced risk for injury. This allows for increased coordination by activating the muscles for a sense of stability and security when running. The end result is more energy, greater endurance and enhanced performance. Features: - Filament fiber for extreme durability - Wide top band for a perfect fit - Extra-flat toe seam prevents pressure points - Anatomical design - Metatarsus compression zone for arch stabilization - Open-pore mesh structure in the calf - Optimized Achilles tendon protector - The hydrophile finish effectively wicks moisture away from the skin for perfect heat and moisture management - Air channels for ventilation in the foot region