Men's Swiftwick Aspire Zero Large - Cobalt Blue The Swiftwick Aspire Zero sock is ideal for running, cycling, triathlon and other endurance sports. A no-show sock that sits below the ankle with minimal extension above your shoe, and will not slide down. DETAILS:  Firm compression provides contoured support and prevents bunching Lightweight Olefin fiber in a minimum cushion design is cool, wicks moisture and dries quickly to keep you performing at your best Y-Heel contour creates a contoured heel pocket that moves with the foot Virtually invisible toe seam eliminates friction in the toe box Mesh footbed and channeled upper increase breathability Made in the USA