Features of the Smartwool Women's Intraknit Merino 250 Thermal Bottom Engineered construction Uses knit structures to enhance Performance with a sophisticated finish Insulating terry loops Are seamlessly paired with mesh ventilation in gender-specific zones designed to balance warmth and breathability 3D Mapping results in near custom Fit and freedom of movement while ribbed elbows provide added durability Knit-in reflective elements enhance visibility in low light conditions 100% Merino yarn provides the full power of merino with unparalleled moisture management, Insulation, thermoregulation, and odor control Fabric Details 97% Merino Wool, 2% Polyamide, 1% Elastane