Back On Track Socks’ Fabric Reflects your Body Warmth and are great for Cold Feet. Constructed of their unique Welltex fabric that’s infused with ceramic powder, these socks reflect your natural body warmth and create a soothing far infrared thermal warmth. Initially, it is recommended that you wear these socks during the day to get used to the warmth that they reflect. Since you move around more during the day, the socks will reflect that much more of your body warmth. Once you’re comfortable with them, you may find that you’d like to sleep with them at night as well. Sold as a pair.