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

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Kari Traa Floke base layer pants blend fine merino wool with tech fibers to create a soft, medium-weight fabric with good warmth, natural odor resistance and breathability for cold-weather activities.

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Great for wearing under other layers, the women's Kari Traa Fryd base layer pants feature a supersoft, quick-drying material that moves with you and cuts out chafing so you can get out exploring.

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When you're giving it all you've got, you need layers that work with you. The women's Kari Traa Fryd base layer pants dry fast, stretch with your body and reduce chafing.

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Harnessing the warming power of Heatwave™ technology, the men's Seirus Heatwave Lite Reversible base layer bottoms reflect heat back to your body, and are now available in a lighter-weight design.

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Harnessing the amazing warming power of exclusive Heatwave™ technology, the men's Seirus Heatwave Reversible base layer bottoms reflect heat back to your body to keep you warm on cold-weather outings.

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Designed to layer under pants or shorts, the men's Smartwool Intraknit Active base layer bottoms help with temperature regulation and moisture management to keep you comfortable while you're active.

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Designed to layer under shorts or pants, the women's Smartwool Intraknit Active base layer bottoms help with moisture management and temperature regulation to keep you comfortable while you're active.

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Stay comfortable on cooler-weather adventures in the Smartwool Intraknit Thermal Merino men's 3/4-length base layer bottoms, which have a performance-enhancing design and a shorter, versatile length.

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The winter-ready pants you need to perform all season, the men's Smartwool Intraknit Thermal Merino Base Layer 3/4 Bottoms use merino wool to help keep you comfortable on every cold-weather outing.

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Built to flex and follow you like a shadow, the men's Smartwool Intraknit Thermal Merino base layer bottoms put warmth first, while 3D knit mesh ventilation helps keep you dry and comfortable.

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Here to help you warm up to cold weather, Smartwool Intraknit Thermal Merino base layer bottoms have 3D-knit articulation that adds an enhanced fit and helps keep you as mobile as ever.

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Built to flex and follow you like a shadow, the women's Smartwool Intraknit Thermal Merino base layer bottoms are 3D knit for insulation, ventilation and flexibility for your high-intensity workouts.

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Made of 100% merino wool, the Wild Rye Jane 7/8 Crop leggings are built to endure the rigors of long days in the mountains. They're cozy enough for apres, but technical enough for weeklong hut trips.

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