Constructed of BOT's unique Welltex fabric that’s infused with ceramic powder, the socks reflect your natural body warmth and create a soothing far infrared thermal warmth. Initially, we recommend that you wear the 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.