Knit material with ultra-fast drying ArmourDry yarns to keep your feet light, dry ;&; cool;ArmourDry yarns help disperse moisture allowing sweat to evaporate quickly;Breathable mesh ventilation zones on top & bottom of foot where you need it most;Bounceback cushioning strategically placed in toe & heel protects high impact areas without added bulk;New Locked-In Fit design keeps sock securely on heel for an adjustment free fit that wont fall down;Arch support helps reduce foot fatigue;Odor control technology reduces odor in the sock;Cushioned back tab with fitted heel that contours around foot for a better fitWe went down to the yarn level to make our fastest-drying socks ever. The fabric evenly disperses moisture, allowing sweat to evaporate more quickly, so you'll run lighter, drier, and cooler.