These socks are made of DANTORU, a high-grade moisturizing fiber that does not lose body heat. The entire inside is finished with a pile knit of insulating fiber (polyvinyl chloride), so it feels good to the touch and warms the entire area from the toes to the ankles. About DANTORU The polyvinyl chloride contained in the material is extremely high in heat retention compared to cotton and wool, and is a high-grade thermal fiber that keeps you warm without letting the body heat trapped inside. It also has excellent quick-drying properties and does not contain moisture. Since sweat and moisture do not accumulate inside, it prevents sweat from getting cold and keeps you comfortable. The back side is all pile products. Due to the nature of knitting and thread, the loop may float slightly to the front side. Please note that the color may transfer or change color to other objects due to friction when sunburned, sweat or water wet. Due to the nature of the material, fluffing and pilling may occur. In addition, washing with water may cause shrinkage, color fading, fluffing, etc., and the texture may change. When washing, put it in a net and press it to wash, and do not wash it with other items. Do not use detergents containing optical brighteners or bleach. Do not leave it in water for a long time or leave it wet. We use fibers that are sensitive to heat. Never dry clean or tumble dry. Also, keep it away from drying with warm air such as heating or anything that causes high temperatures, such as hand warmers. (*If the thread shrinks due to high temperature, it will shrink and will not return to its original state*)