Altera Men's Prevail Medium Weight Over The Calf Socks 54% Alpaca Fiber 15% Nylon 1% Silver 5% Spandex 25% hydrotec Made in US Alpaca hollow core fiber wicks moisture away from your feet offers supreme comfort Premium Terry Loop Construction Built-in Arch Support Cushioning Reinforced Heel & Toe Unconditional Lifetime Warranty Alpaca hollow core fiber wicks moisture away from your feet offers supreme comfort