The Smartwool Men's Merino 250 Baselayer Tights have beenupdated to bring you a better fitting, more functional tight. It is made of Merino 250 a heavier, soft, 100% Merino wool fabric offers breathable warmth, moves sweat away from the body, and provides next-to-skin comfort in colder conditions. Flatlock seam construction minimizes chafing. Smartwool's heaviest weight wool fabric will help keep you warm and comfortable as you ski, run, and hike the day away.