Tackle the cold without sacrificing on-mountain mobility in this Obermeyer Clara quarter-zip base layer top. Soft and stretchy and with flat seams, it's a comfy layer with a dynamic, natural fit.

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A great top for any season, the Smartwool Classic All-Season Merino top wicks moisture and regulates temperature, making it ideal as a fall base layer or a single layer when summer backpacking calls.

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With a form-hugging fit, the Smartwool Classic All-Season Merino Lace long-sleeve tee is a great first layer for high-energy activities—like hiking, jogging or rowing crew—in cool or warm weather.

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With its soft and durable merino wool blend, the men's Smartwool Classic All-Season Merino long-sleeve base layer top is game for any adventure from spring skiing to winter hiking.

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Made from a lightweight jersey, the women's Smartwool Classic All-Season Merino long-sleeve base layer top is just as comfy layered under your ski jacket as it is worn alone for summer backpacking.

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Game for any adventure, any time of year, the men's Smartwool Classic All-Season Merino quarter-zip base layer top is made from a lightweight jersey and built for comfort—even under your pack.

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Designed to be your go-to for warm or cold weather, the women's Smartwool Classic All-Season Merino quarter-zip top features lightweight, soft merino wool with a nylon core for increased durability.

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Made from their lightest-weight jersey and built for comfort, the women's Smartwool Classic All-Season Merino quarter-zip base layer top is game for any adventure, any time of year.

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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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