Oh so soft and not itchy, the kids' REI Co-op merino midweight base layer top is an ideal first layer for cold weather. It naturally regulates temp and is certified to the Responsible Wool Standard.

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Built with the outdoor enthusiast in mind, the men's Smartwool Merino Sport long-sleeve quarter-zip top provides thermoregulation, odor resistance and durability for years of adventure.

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Stay dry, warm and stoked all day with the men's Burton Midweight Base Layer Crew top, which gives you moisture-wicking fabric and comfortable, chafe-free seams.

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Hard-charging winter days start out cold, but you always warm up. The men's REI Co-op Midweight Base Layer half-zip top offers the warmth of long sleeves and the easy venting of a front zipper.

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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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Make your kiddo's base layer the warm, breathable, kids' REI Co-op Midweight Crew long underwear top and they'll play happily outside all day. It's great on its own for inside play, too.

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Make your tot's base layer the warm, breathable, toddlers' REI Co-op Midweight Crew long underwear top and they'll play happily outside all day. It's great on its own for inside play, too.

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Warm and wicking to keep you comfortable on the slopes, the men's REI Co-op Midweight Long-Sleeve Base Layer has a smooth face to easy layering and a brushed back for warmth against the cold.

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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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Begin your layering system with a flexible base that moves with you. The men's Burton Midweight X Base Layer Crew top also breathes with your body heat and helps control odors.

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Begin your layering system with a flexible base that moves with you. The women's Burton Midweight X Base Layer Crew top also breathes with your body heat and helps control odors.

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Pull up the hood, deploy the face mask and ride into the weather. The women's Burton Midweight X Base Layer Long Neck hoodie keeps you comfy with a built-in neck warmer and breathable fabric.

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Pull up the hood, deploy the face mask and ride into the weather. The men's Burton Midweight X base layer long-neck hoodie keeps you comfy with a built-in neck warmer and breathable fabric.

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Make layering easy with the chafe-free seams and practical thumbholes of the men's Picture Organic Clothing Nangha base layer top. It's also moisture-wicking and treated to help control odors.

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