The Darn Tough No Show Tab Ultra Light Merino running sock weighs only 13 gm per sock. The sock features merino wool, fine gauge knitting, fast action wicking and true SeamlessT to offer an ultra smooth, invisible feel. The sock is guaranteed for life and is naturally antimicrobial. The no shoe height sock provide a lighter than air feel. It comprises of 54% nylon, 40% merino wool and 6% lycra? spandex.