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

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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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Ideal for cold weather, the kids' REI Co-op merino midweight base layer bottoms are soft—not scratchy—naturally regulate temp and made with wool that's certified to the Responsible Wool Standard.

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Your underwear should deliver lasting comfort. Whether you're spending the day at work or a couple hours at the gym, Smartwool Merino Plant-Based Dye boxer briefs help you stay confidently comfy.

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A wide, merino-lined elastic waistband and flatlock seams help make Smartwool Merino Print boxer briefs your new favorite for any activity—from urban exploration to new trail adventures.

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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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An ideal performance layer, the men's REI Co-op Midweight Base Layer Bottoms boast a smooth face and low-bulk seams for easy layering and a brushed back for added warmth and comfort.

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Stay dry, warm and stoked all day with the men's Burton Midweight Base Layer pants, which give you moisture-wicking fabric with a cottonlike feel and a plush waistband.

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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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The kids' REI Co-op Midweight Long Underwear Bottoms are warm and very good at wicking moisture, making them an ideal base layer for highly aerobic cold-weather fun, like skiing and snowshoeing.

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The toddlers' REI Co-op Midweight Long Underwear Bottoms are warm and very good at wicking moisture, making them an ideal base layer for highly aerobic cold-weather fun, like skiing and snowshoeing.

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Shred to your heart's content with the comfort of these men's Midweight X base layer bottoms. They're your quiver-of-one, serving up quick-drying, stink-free warmth for long days on the mountain.

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