Under Armour Men's UA HeatGear Coreshort Prima Patented X-Shaped Elastic Support System - Supports your core and keeps your muscles aligned. Second-Skin Fit - Keeps your muscles fresh and reduces recovery time. 4-Way Stretch Fabric - Allows you to move freely and comfortably. Moisture Transport System - Wicks moisture from your skin, keeping you dry and comfortable. Heatgear Technology - Keeps you dry, no matter how how it is.