Our Merino clothing is made from super fine, sustainably sourced 100% Merino Wool, our Merino 250 base layer is technically long underwear, and technically awesome. Our Merino 250 base layer is the core of our Smartwool layering system and designed to work in concert with our SmartLoft midlayers (or your favorite outerwear) to protect you against the elements. The magic of Merino wool products are how they work with your body to thermoregulate. The fine Merino 250 fibers are coiled in such a way to move moisture away from your body before becoming liquid, keeping you dry longer if you start heating up. The result? You can go farther, and stay out longer. Check out our new women’s Merino base layers and our Merino base layers for men.