You've probably seen Zoot's Ultra CompressRx Socks on some of the world's top triathletes. Why? They provide numerous benefits. Zoot consulted doctors in the field of medical compression and came up with a circumference-based fit system so you not only get the perfect fit, you get the right amount of compression. The result is CompressRx graduated compression technology which surrounds your muscles to help stabilize them, increasing response and reducing vibrations and micro-damage that lead to post-exercise soreness. After exercise, these socks reduce edema and encourage blood flow back to the heart which flushes lactic acid. Made from SynchroRx polypro/spandex with SilverTech, these socks boast Achilles tendon support and comfy, padded foot beds.