Okamoto Socks Supplement - Authentic Black, 25cm length Gray, length up to the calf Set of 2 Brand new, unused. Just slip them on when you feel cold, and they'll be warm and cozy. They wrap your feet gently, providing a comfortable warmth, like being in a kotatsu (heated table). Using Okamoto's uniquely developed special insulation and heat-generating material, we've created even warmer leg warmers. The secret is the warmth stimulation at the ankle. The ankles, which are prone to feeling cold, are covered with heat-generating material. The San'in-ko (acupressure point) on the ankle is warmed by thermal stimulation (patent pending*). (*Thermal stimulation, Patent No. 6043982)