Boys' UA Diamond Armour(TM) Baseball Shortsleeve - $29.99

This is it, the most technical baseball baselayer we've ever made, with every single detail engineered for what you do on the field. It stretches and moves with you so smoothly you don't even know it's there. Ventilation exactly where you need it. With this shirt under your jersey, you'll only be focused on one thing: winning. Allover embossed lightweight fabric that layers easily under a uniformStretch-mesh back panel provides strategic ventilation4-way stretch fabrication allows greater mobility and maintains shapeSignature Moisture Transport System wicks sweat away from the bodyQuick-dry fabrication keeps you light and comfortableAnti-odor technology prevents the growth of odor causing microbesRaglan sleeve construction and flatlock stitching allow a full range of motion without chafing Extra length to stay tucked inPolyester/ElastaneImported - $29.99