Moisture-wicking and quick-drying, the men's REI Co-op Active Pursuits long-sleeve T-shirt protects you from morning chill, midday sun and trailside brambles.

Shirts ParentShirts

With a new softer feel, the men's REI Co-op Active Pursuits 2.0 quarter-zip shirt is ideal for cool-weather workouts: warm before and after; breathable and wicking so you don't overheat during.

Shirts ParentShirts

Breathable warmth and 4-way stretch make the women's REI Co-op Active Pursuits quarter-zip a natural for cool-morning running—and whatever else comes next in your day.

Shirts ParentShirts

Daydreaming about summer days on the trail? Include the REI Co-op Active Pursuits T-Shirt and imagine yourself staying supremely cool and comfortable on those sunny switchbacks.

Shirts ParentShirts

You can work up a sweat and still feel cool with the women's Smartwool Active Ultralite long-sleeve T-shirt. With its soft, lightweight and comfy feel, this top is great for high-energy activities.

Shirts ParentShirts

Keep things breezy in the summer with the women's Smartwool Active Ultralite V-neck T-shirt. Great for trail hikes and yoga classes, it's light, soft and built to keep you cool.

Shirts ParentShirts

Built with bestselling ActiveIce™ technology, the women's Outdoor Research ActiveIce Spectrum Sun long-sleeve tee helps keeps you cool and protected in hot, sweaty, sun-baked conditions.

Shirts ParentShirts

The months of early morning runs and cross-training have paid off—now that you're toeing the starting line, it's time to kick into high gear in the moisture-wicking adidas Adizero T-shirt.

Shirts ParentShirts

A lightweight performance shirt that looks and feels good? Yes, please. The Marmot Aella shirt features AirExchange tech, which allows plenty of air to pass through the fabric to keep you cool.

Shirts ParentShirts

Head off-road for a quick hike and then head back into town in comfort and confidence in the men's Marmot Aerobora shirt. Its heathered slubbed fabric breathes well and dries fast.

Shirts ParentShirts

The men's Mountain Hardwear Air Mesh Half-Zip pullover may look unassuming, but once you have it on, you won't need anything else. Its active mesh fabric keeps you comfortable in a variety of temps.

Shirts ParentShirts

Single layers can have a bigger impact than you think. The women's Mountain Hardwear AirMesh half-zip pullover's lightweight mesh/fleece fabric absorbs sweat, dries quickly and insulates in the cold.

Shirts ParentShirts

Incredibly warm for its weight, the women's Mountain Hardwear AirMesh hoodie is made of lightweight mesh/fleece fabric that absorbs sweat, dries quickly and insulates in the coldest conditions.

Shirts ParentShirts

A single layer can have a bigger impact than you think. The men's Mountain Hardwear Air Mesh long-sleeve crew top may look unassuming, but once you have it on, you won't need anything else.

Shirts ParentShirts