Smartwool Men's Classic Thermal Merino Base Layer Crew SKU: SW016349M15 Details: Meet the better-than-ever Men's Classic Thermal Merino Base Layer Crew. We've updated this 100% Merino wool fan-favorite with new colors and a new fit to improve functionality while enhancing aesthetics. Shoulder panels eliminate top shoulder seams and a flatlock seam construction helps prevent chafing. Add one of our best base layers for cold weather to your winter wardrobe and experience the difference the next time you go skiing, hiking, climbing, or biking.