Function: 1. Cotton Material: Made of high-quality cotton material, these socks are soft, breathable, quick-drying, and feature a strong elastic band for a good wearing experience! 2. Self-heating: There is a tourmaline pattern under the socks that heats up to help your feet relax and unwind in cold weather. 3. Wide Application: These socks are suitable for all kinds of outdoor activities, such as mountaineering, skiing, fishing, jogging, and are suitable for camp work, snow removal, etc. 4. Universal Size: These socks have a universal size, which can relieve leg fatigue, relieve pain, regulate the nervous system, keep warm, remove moisture, etc. Take them for sure! 5. Gifts for People: Featuring both practicality and one size fits all, these socks are perfect gifts to send to parents, friends, a very useful gift! Specification: Item type: self-heating socks material: cotton Size: Free Size Package List: 4 x self-heating socks