Smartwool updated the fit of the Smartwool Men's Classic Thermal Merino Base Layer 1/4 Zip to improve functionality while also enhancing aesthetics. As one of the heaviest base layer tops and best base layers for cold weather, this garment uses 100% responsibly sourced Merino wool, shoulder panels, and a flatlock seam construction to help minimize chafing as well as help keep you comfortable and temperature-regulated as you enjoy high-intensity skiing, hiking, running, and more. FeaturesSlim fit is intended to follow the contours of the bodyFabric helps combine the moisture management, temperature regulation, and odor resistance of 100% Merino wool with interlock knit for comfortFlatlock seam construction and offset shoulder and side seams designed to help increase comfort and minimize chafingSide seams wrap to front