Smartwool's best selling and warmest base layer just got a little more refined with a subtle pattern, an improved fit, chafe-free seam construction and panels that offer more comfort with a pack. This heavier, soft, 100% Merino wool fabric offers breathable warmth, moves sweat away from the body, and provides next-to-skin comfort in colder conditions. Slim Fit Interlock knit provides ultimate comfort Crew neck with set-in sleeves Shoulder panels eliminate top shoulder seams Flatlock seam construction designed to eliminate chafing Knit in Vietnam: 100% Merino Wool Garment Weight: 255 g = 9 oz