Made with 85% polyester and 15% lycra Made of technical anti-micro bacterial lycra« from DuPont Extra tall to cover most of your calf Provides heat on the top and bottom of the toes The ZEPTO« fiber heat technology covers entire foot area providing uniform heat Custom fit design for left and right feet Fits under tall or short boots Each sock uses 12 volts Socks (as a pair) draws 1.4 amps of current to produce 19 watts of heat. SOCK HEATED GEN X4 BK MD