35 Below Socks are made of aluminized thread with aerospace fabric technology that reflects your own body heat, keeping you warm in any weather. The socks are incredibly lightweight with a flexible material, so they are thin enough to wear underneath regular socks yet durable enough to wear alone. 35 Below Socks are developed to reflect heat in severe cold to keep your temperature just right, and they’re great for men, women and children.  Get 3 pairs – black or white – for $19.99 with Free Shipping.