An all-season favorite, the Merino 150 Long-Sleeve works as a base layer in fall or as a single layer when summer backpacking calls. Featuring Core Spun technology, its construction wraps Merino around a nylon core for added durability while still keeping the ultra-soft material's temperature regulation and moisture-management benefits right next to the skin. Raglan sleeves remove shoulder seams for comfort under a pack, and smooth merrow stitching wraps from side to front for a flattering look. 87% Merino Wool13% Nylon Core. Merino 150: Smartwool's lightest, most versatile layer with enhanced durability and ultimate breathability. Quick drying, it works as a solo layer in warm weather or as a base layer in cool weather. Core Spun: Merino fibers wrapped around a nylon core for added durability while still keeping the comfort of Merino next to skin. Slim Fit. Raglan sleeve design removes shoulder seams. Side seams wrap to front for a body-enhancing fit. Stretch merrow stitching for comfort and a feminine aesthetic. Garment Weight: 4.7 oz. (133 g). Knit in Vietnam.