Soft, breathable and naturally odor resistant, the ultrafine merino wool of the men's REI Co-op Merino 185 long-sleeve base layer top is beloved for both sweating on the trail and just sleeping.

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

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Built with soft merino, the Icebreaker Merino 200 Sonebula Long-Sleeve High-Neck Thermal top regulates body temperature in all weather conditions while resisting odors. High collar adds coverage.

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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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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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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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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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Beat the heat on summer adventures in the Odlo Performance Light Crew shirt. Organic body mapping and integrated ventilation zones provide ideal breathability when you're working up a sweat.

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Made from lightweight pin-dot mesh, this men's Saxx Quest long-sleeve crew base layer top is a versatile option for whatever your day has in store. Test it out on a quick hike or a misty morning run.

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Lightweight and supple, the REI Silk crew shirt provides great warmth for its weight and offers luxurious comfort.

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