Thank you for viewing! The brushed material used on the inside mainly uses hollow fibers, which have low thermal conductivity, providing excellent quick-drying properties and stretch. It's a thermal brushed material using polyurethane, which has a heat-generating effect. These are 3mm thick, split-toe winter socks. Retail price: 15,950 yen I'm selling these because I replace them every few years. Please understand that these are used items before purchasing. They are not completely waterproof. No returns or claims, please.