Patented and engineered with heavyweight pads for rugged hiking. Thorlo's provide extra padding at the ball and heel which reduces the destructive forces of foot strike. Thorlo's allow the shearing movement that normally occurs within the surface tissues of the foot to occur within the exclusive fabric. This protects the foot from activity specific stresses, blister and calluses, which are the root causes of most of your foot problems. Thorlo's patented lower density pad in the arch area allows the boot to naturally snug closer and facilitate better control of your foot. Thorlo's Ski Wool/silk is made of 27% Wool, 27% Silk, 27% Thorlon Acrylic, 3% Spandex, 16% Stretch Nylon. The Thorlo Ski Light Wool/Silk is made of 33% Wool, 33% Silk, 19% Stretch Nylon, 13% Olefin, and 2% Spandex. Research shows: Thorlo's keep your feet drier than “Ordinary Socks”. Thorlo's reduce plantar pressure. Thorlo's reduce and prevent the destructive shear forces between your foot and shoe. Thorlo's increase circulation in your feet. Thorlo's keep your feet at a more balanced temperature. Thorlo's facilitate better posture. Professionals prefer Thorlo's over “Ordinary Socks”. Men's and Women's sizes available.