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For strictly no-fuss performance, look to the AA 1/4ber-high-tech X-Bionic Women's Vitalizer X-Shirt. X-Bionic, an award-winning Swiss company, designed the Vitalizer X-Shirt with an intricate system of air channels, canals and storage niches into the X-Shirt's center and underarms for precise thermoregulation. No matter how hard you sweat, a calculated amount of moisture remains on your skin to cool it, while the rest is drawn away by the garment's fibers. Additional channels across the front of the shirt transfer air, heat and moisture to areas of the body where evaporation has no negative cooling effect on organs or muscles. A snug yet elastic fit gives you a wide range of motion when you're on the trail or working out.