Built for 4 seasons, the men's Smartwool Classic All-Season Merino Base Layer bottoms keep you comfy on snowy days or summer nights under the stars with durable wool-blend fabric and an updated fit.

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When layering for mild-weather adventures, start with the women's Smartwool Classic All-Season Merino base layer bottoms. They're made from lightweight jersey with a supersoft next-to-skin feel.

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Whether you're skiing, hiking or running, Smartwool Classic Thermal Merino 3/4 base layer bottoms provide reliable comfort and breathability with an updated fit to minimize sag and keep you going.

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When the mercury dips and your kiddo heads out to play, the kids' Smartwool Classic Thermal Merino base layer bottoms offer breathability, natural stretch and a layer of warmth for cold-weather fun.

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Updated with a better fit and reliable, resilient merino wool, the men's Smartwool Classic Thermal Merino base layer bottoms keep you comfortably warm through winter and all year long.

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Update your cold-weather kit with tights that adapt to your activity. Smartwool Classic Thermal Merino base layer bottoms offer cozy warmth for stop-and-go activities and feature an improved fit.

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Serving up warmth for stop-and-go activities and an improved fit, the women's Smartwool Classic Thermal Merino base layer bottoms in plus sizes are a reliable, cozy addition to your cold-weather kit.

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Yoga-inspired leggings with ample stretch in the single-sided brushed stretch jersey knit, Obemeyer Courtnay leggings provide unrestricted movement and an active fit.

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A versatile winter essential, the girls' Obermeyer Courtnay leggings can be worn as a base layer on the mountain or casual pants back at the lodge.

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Whether you layer them or wear them on their own, Obermeyer Discover tights offer a flatseam construction for comfort, a soft brushed interior and fun one-of-a-kind colors and prints.

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Great for layering to add warmth on active days out—or wearing solo cozied up in your tent—the women's Kari Traa Elenore base layer tights are made with soft wool for a comfortable next-to-skin feel.

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Offering superior temperature regulation without the bulk, tasc Performance Elevation Merino men's base layer bottoms deliver light warmth and moisture management for cool-weather outdoor activity.

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Offering superior temperature regulation without the bulk, the women's tasc Performance Elevation Merino base layer bottoms deliver warmth and moisture management for cool-weather outdoor adventures.

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An ideal base layer for getting vert or counting off switchbacks, these men's Artilect Flatiron 185 leggings provide soft, breathable warmth while you explore outdoors.

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