Naturally odor resistant, the ultrafine merino wool of the soft, breathable women's REI Co-op Merino 185 long-sleeve half-zip base layer top is ideal for sweating on the trail—and sleeping in a tent.

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For everything from sleeping to sweating on the trail, the ultrafine merino wool of the women's REI Co-op Merino 185 long-sleeve half-zip base layer is ideal. It's soft, breathable and odor resistant.

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Improved with a new fit and colors, the women's Smartwool Merino 250 Base Layer Crew top helps you look and feel better with perfect midweight warmth and dry comfort for your active best.

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Warm merino bottoms for the coldest months, the women's Icebreaker Merino 260 Tech High Rise base layer leggings are great for winter layering on skiing, snowshoeing or other cold-weather adventures.

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Layering is smart when you know the mercury will dip and rise on your hike. The Smartwool Merino base layer tee works well undercover on cool mornings or as a standalone piece in warmer temps.

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Stay dry on the trail in the soft, breathable and naturally odor-resistant REI Co-op Merino Merino Bikini Underwear for women. They're made to keep you comfy throughout the day.

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Move with ease and layer to your heart's content with the the low-impact REI Co-op Merino Bralette, made with a sweat-wicking merino wool blend and ready for the day ahead.

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Stay dry on the trail in the soft, breathable and naturally odor-resistant REI Co-op Merino Merino Hipster Underwear for women. They're made to keep you comfy throughout the day.

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For reliable comfort at your very first layer, here's a go-to choice. Cut to fit your curves, this Smartwool Merino Lace thong breathes, wicks moisture, regulates temperature and resists odor.

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Avoid panty lines on the trail in the soft, breathable and naturally odor-resistant REI Co-op Merino Merino Thong Underwear for women. They're made to keep you comfy throughout the day.

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Keep the winter chill away with the women's Icebreaker MerinoFine base layer leggings, which feature a high waist for added coverage—and its merino wool is naturally stretchy and odor resistant.

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The women's REI Co-op Midweight Base Layer Half-Zip Top offers warmth in the cold with long sleeves and easy venting thanks to a front zipper.

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Start with a high-performing next-to-skin layer and take advantage of the snow. The women's REI Co-op Midweight Base Layer Tights have a smooth face for easy layering and brushed interior for warmth.

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Wherever you're out in the cold, you'll love the streamlined warmth, moisture-wicking comfort and easy layering of the women's REI Co-op Midweight long-sleeve base layer top.

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