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Just because the temperature is dropping doesn't mean your metabolism has to follow. The REI Activestretch half-zip top offers cozy comfort that will heat up your workout routine. Quick-drying Activestretch fabric features a moisture-wicking fleece inner face and a smooth outer face that's perfect for aerobic activity in cool weather. Deep front zipper with a tall collar keeps frosty mornings from chilling your skin. Thumb loops keep sleeves in place when your arms are in motion. Droptail hem increases rear coverage. Ergonomic seam placement and stretchy fabric complements your natural movements. Reflective trim increases safety in low light. Athletic fit moves with you and stays close to your body. Fabric offers a UPF rating of 50+.