This is a four season sock, great cushioning and support for standing in a river tossing flies at salmon, long hikes, hard hunts, and basically just keeping your feet dry and comfortable in most conditions. URfit System for arch support and memory-knit construction Smooth and flat comfort toe seam Footbed is a luxurious bison down, ultra-fine merino, bamboo blend Leg Shaft is an extremely comfortable military-spec polypropylene 33% Bison Down 33% Ultrafine Merino Wool 33% bamboo fiber Made in USA