Our Primaloft Lightweight socks utilize Primaloft polyester yarn to keep your feet warm in a variety of temperatures, all without overheating or being excessively bulky. Features Primaloft polyester yarn offers the best thermal performance to weight in a wide temperature range. Calf High - 18cm/7in with seamless toe construction. Fabric Content: 45% Polyester, 25% Polypropinene, 25% Polyamide, 5% Elastane.