A chill in the air can make training better, especially when you control your warmth with the ultralight insulation and 4-way stretch of the women's REI Co-op Swiftland half-zip pullover.

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A cold snap can actually spice up your daily run—especially when you take control of your warmth with the ultralight insulation and 4-way stretch of the women's REI Co-op Swiftland half-zip pullover.

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The more you run, the more you'll love the men's REI Co-op Swiftland long-sleeve T-shirt—it's made with microventilated SwiftTex™ fabric that's so light and cool it's like running in nothing at all.

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Sweat happens. The women's REI Co-op Swiftland long-sleeve T-shirt handles it easily—with microventilated SwiftTex™ fabric that's so light and airy you won't even notice it's there.

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You can't make the day any cooler, but you can wear the women's REI Co-op Swiftland long-sleeve T-shirt—it cools you with microventilated SwiftTex™, a fabric so airy and light it's barely there.

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If you like running long trails on warm days, you'll love the men's REI Co-op Swiftland T-shirt—it's made of microventilated SwiftTex™, a fabric so airy and cool it's barely heavier than the breeze.

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Forget the heat and focus on the fun. The women's REI Co-op Swiftland short-sleeve T-shirt is made with microventilated SwiftTex™ fabric that's so airy and cool you won't even notice it's there.

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You can't outrun heat, but you can run cool in the women's REI Co-op Swiftland short-sleeve T-shirt. It's made with microventilated SwiftTex™, a fabric so light and airy you barely know it's there.

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Break a sweat and keep your cool. The women's REI Co-op Swiftland tank top is made with new microventilated SwitftTex™ fabric that's so light and airy it's like wearing nothing at all.

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For afternoons pedaling in the city or up and down hills through the countryside, the women's Marmot Switchback long-sleeve shirt is made in a lightweight rib-knit fabric that has an extra-soft feel.

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A bit of a throwback to the summer camp days, the Marmot Switchback tank top is crafted from a blend of natural and synthetic fibers, which gives it a soft feel for hiking, climbing and daily wearing.

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Don't let the casual style fool you: This men's DAKINE Syncline short-sleeve bike jersey sheds sweat, resists odors and follows your every move from rocky, muddy trails to post-ride chill sessions.

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Built to keep you dry and comfy after sweaty trail sessions, the men's DAKINE Syncline long-sleeve mountain bike jersey goes from trailhead to "let's grab a pint" without missing a beat.

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Made for the modern hiker who takes a fresh, unconventional approach to life, style and the trails, the Marmot Syrocco shirt breathes easily and dries fast, so you stay cool from trailhead to brewpub.

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