Air it out on the trail, at the crag, or by the water—this go-to base layer keeps your core covered while letting your arms fly free. AirExchange performance fabric is breathable and quick-drying, so you can stay active without accumulating heat or moisture. When the sun pops out and outer layers come off, UPF 50 protection keeps you safe from blazing rays. Dropped shoulder and abrasion-resistant seams keep you comfy, agile, and chafe-free when you’re wearing a pack or racking sling, even when you’re racking up miles or vert from early morning to after sunset. Need to snag a snack or lip balm on the move? A hidden zip-secure pocket is accessible even when you’re buckled into a harness or your backpack hip belt.