The "Marude Kotatsu" series uses patented technology to warm your body from the feet up. By using a special material to provide thermal stimulation to the "Sanyinko" acupressure point on the ankle, you can feel warm from the inside out! Two pairs in easy-to-use black. Perfect for gifts! 23-25cm Cold protection, cold prevention, heat retention, heat generation, fertility treatment, cold sensitivity, cold countermeasures