With a technical, zip-neck design and 100% merino wool construction, the men's Icebreaker 260 Tech Half-Zip base layer top is a breathable foundation for cold-weather layering and active days outside.

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An all-seasons base layer, this men's Arms of Andes 300 Lightweight Alpaca Wool Half-Zip top is breathable for summer hikes and warm from the slopes to apres-ski in winter.

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Your active, high-intensity lifestyle calls for the Craft Active Intensity base layer top. Wear this bestseller for training, running and skiing, whether it's cross-country or backcountry.

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Your active, high-intensity lifestyle calls for the Craft Active Intensity zip base layer top. Wear this bestseller for training, running and skiing, whether it be cross-country or backcountry.

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Face every challenge with the men's Artilect Boulder 125 Crew base layer top. It combines merino wool and nylon for an incredibly soft, durable fabric that stretches with you—and retains its shape.

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Dump heat—or add more—with the thermoregulating ventilation of the men's Artilect Boulder 125 Quarter-Zip base layer top. It stretches with you and keeps its shape after all your adventuring.

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Worn as a technical training base layer for outdoor activities, the Threads 4 Thought Brennan base layer long-sleeve quarter-zip top is soft and stretchy and has all the tech qualities you seek.

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High performance in cooler months begins with a great base. Working from the inside out, this Craft CORE Dry Active Comfort base layer top is soft and functional—essential to your winter gear.

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Lightweight, soft and warm, the men's Patagonia Capilene Air base layer hoodie insulates even when wet, dries quickly and resists odors for days of use whether you're on the trail or the slopes.

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Lightweight, soft and warm, the men's Patagonia Capilene Air crew base layer top dries quickly, insulates even when wet and resists odors for days of use whether you're on the slopes or the trails.

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Warm, breathable and quick-drying for daily wear, the men's Patagonia Capilene Midweight Crew base layer top incorporates HeiQ® Fresh durable odor control to cut the funk and keep the fabric fresher.

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Stay cozy on chilly forest treks and snowy alpine adventures. An ideal choice for cool-weather quests, the men's Patagonia Capilene midweight zip-neck base layer top keeps you comfy on the move.

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

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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.

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