The Boys' Under Armour ColdGear® Mock Long Sleeve Shirt is a great base layer for your young athlete. Made from dual-layer fabric, this Under Armour Boys' ColdGear® Mock Shirt features a brushed interior for warmth and a smooth exterior for quick drying. With the four-way stretch, he'll enjoy a maximum range of motion when staying active in cold weather conditions. Plus, the fitted construction and mock neckline help to trap and retain body heat better.