The Smartwool Classic Thermal Merino Base Layer 1/4 Zip for men has been updated to improve functionality while also enhancing aesthetics. As one of their 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.