The heat sock 5.1 from Lenz simply warms cold feet away. They fit snugly around the foot and leg and, with the help of their battery-operated, three-stage heat function, keep the lower extremities at a pleasant temperature in all weather conditions. The slim lithium packs (not included in the scope of delivery) can be attached to the sock cuff - barely noticeable below the knee - using press studs. The big cold can come. With the heat sock 5.1. you are well prepared for it.