Smartwool® updated the fit of their Men's Classic Thermal Merino Base Layer 1/4 Zip 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. 100% Merino wool fabric made with an interlock knit for comfort, breathability, thermoregulation and odor resistance Flatlock seam construction and offset shoulder and side seams designed to help increase comfort and minimize chafing Side seams wrap to front 10" (25 cm) center-front zipper with semi-locking slider Slim Fit: intended to follow the contours of the body Product Features: Fabric:100% Merino Wool SmartWool Men's Classic Thermal Merino 1/4-Zip Base Layer Top