The new and improved Women's Classic Thermal Merino Base Layer Pattern 1/4 Zip is here to bring you a better feeling, better performing, and better-looking garment. As one of Smartwool's 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 keep you comfortable and temperature regulated as you enjoy high-intensity skiing, hiking, running, and more.