SmartWool Women's Saturnsphere Socks 21% nylon Merino Wool - Knitted in Vietnam, Merino is nature's most technical, high-performance fibre. Its complex structure makes it remarkably soft against your skin, helps regulate your body temperature, and stays looking great wear after wear. 4 Degree Fit System - 4 Compression Bands and flex zones that provide high performance and a secure fit. High Density Impact Zones with WOW Technology - Higher density SmartWool Duroyarn in the heel and metatarsal areas offer added protection and durability. Toe Seaming - Flat-Knit toe seaming provides increased comfort and durability. Moisture Management - SmartWool fibers absorb and evaporate moisture so feet stay drier for longer.