The Tundra Aerogel Socks uses NASA-trusted technology to deliver the perfect socks for long, frigid winter days in alpine environments. Insulated with PrimaLoft® Gold insulation, these socks are water-repellent, breathable, and packable, and the Pertex® Quantum shell is windproof and water-resistant. They feature an updated design with an ankle cinch top and an anti-slip sole. Whether exploring the Arctic or needing reliable protection against cold winter winds, the Tundra Aerogel Socks are an excellent choice for anyone seeking the ultimate warmth and comfort. Worn a couple of times- great for camping and cross country ski!