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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Made from premium merino wool, the Smartwool Classic Thermal Merino Crew base layer top helps regulate your temperature with improved performance functionality while hiking or skiing in cold weather.

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Delivering exceptional performance and improved functionality, the women's Smartwool Classic Thermal Merino crew top maintains your warmth and active comfort as you hike, ski, bike and more.

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Made of heavyweight merino wool, the men's Smartwool Classic Thermal Merino quarter-zip base layer top helps regulates your temperature during high-intensity skiing, hiking or running in cold weather.

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Made of heavyweight merino wool, the men's Smartwool Classic Thermal Merino quarter-zip top helps regulates your temperature during high-intensity skiing, hiking, running and more in cold weather.

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Whatever high-intensity activity you get into, the women's Smartwool Classic Thermal Merino quarter-zip top delivers exceptional performance and improved functionality to keep you warm, dry and comfy.

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Stay comfortable, dry and warm in the plus-size Smartwool Classic Thermal Merino quarter-zip top while enjoying your favorite activities year-round. An improved, active-minded fit is designed to move.

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Take your workout away from the studio and into the park. With breathable fabric and low-impact support, the printed Athleta Conscious Crop top for A–C cup sizes keeps you breezy during summer yoga.

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Delivering light support that's suitable for most types of workouts, the Craft Core Charge sport top is made in a soft, functional recycled polyester and elastane jersey.

UnderwearSports Bras

Made for all types of winter activities, this Craft Core Dry base-layer set has flatlock seams that enhance your comfort while the brushed jersey interior offers optimal warmth.

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