The Darn Tough Vertex No Show Tab Ultra Light running sock is ultra light. 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 53% nylon, 41% merino wool and 6% lycra? spandex.