Our Men's Classic Thermal Merino Base Layer Colorblock Boxed Crew features 100% Merino wool made with a flatlock seam construction and offset shoulder and side seams designed for enhanced comfort, breathability, thermoregulation, and odor resistance. From hiking to running and skiing, this base layer brings consistent comfort, plus reliable warm th and durability, for every winter activity. Smartwool Mens Classic Thermal Merino Base Layer Features: Our slim fit is intended to follow the contours of the body Fabric helps combine the moisture management, temperature regulation, and odor resistance of 100% Merino wool with interlock knit for comfort Flatlock seam construction and offset shoulder and side seams designed to help increase comfort and minimize chafing Side seams wrap to front