Thorlos Experia Unisex XCCU Multi-Sport Thin Padded Low Cut Sock 65% Thor-Wick COOL polyester, 20% Nylon, 14% polyester, 1% Elastic Made in USA No Closure closure Turn Inside Out / Machine Wash / Use Liquid Fabric Softner Powered by specially sculpted Thorlos pads in the ball and heel provide protection from friction, the primary cause of blisters, and impact protection where needed most. Ultra-lightweight sock frame made of Lycra mesh provides contoured aerodynamic glove-like fit and maximum breathability Achilles-tendon pad protects the heel from rubbing/chaffing/blistering, while also functioning as a heel lock, assuring your sock won't slip down into your shoe Runner's World Gear Award Winner called "the best of both worlds" Padding Level: Sculpted Thin Cushion Guarantee - Your feet will feel better or your money back