When a foot-wide ledge becomes your bed for the night, this compressible zip-neck helps turn up the heat.

Underwear TopsBase Layer Tops

Designed with adjustable straps that you can wear 2 ways, the prAna Chakara crop top is made from a recycled nylon blend that is lightweight and moisture-wicking to keep you comfortable on the go.

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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.

Underwear TopsBase Layer Tops

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.

Underwear TopsBase Layer Tops

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.

Underwear TopsBase Layer Tops

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.

Underwear TopsBase Layer Tops

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.

Underwear TopsBase Layer Tops

Made for year-round adventures, the women's Smartwool Classic All-Season Merino tank top delivers the thermoregulating, breathable powers of merino wool to keep you cool in summer and warm in fall.

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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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