Thermolite?? insulating fibers provide gentle compression & wicking for warm, dry feet. Cushioning on the sole & shin protect you from bumps and bruises. Contoured rib top holds sock in place to eliminate slippage. Spandex compression zones add support and keep sock in place all day long. Mesh panels vent moisture while trapping heat inside. Reinforced toe and heel add comfort and longer product life. 61% Thermolite?? polyester, 37% nylon, 2% spandex. Lightweight.