The Smartwool PhD Outdoor Light Micro is specially made for the trail. It features Indestructawool technology for ultimate durability and comfort. These socks have been designed to outlast your greatest adventures. It includes features like mesh zones for maximum breathability, a Virtually Seamless toe, and 4 DegreeTM Elite Fit System. It is made of 60% Merino Wool, 38% Nylon and 2% Elastane.