Under Armour Boys' HeatGear Armour Up Fitted Shorts &ndash; Long 90% Polyester, 10% Elastane Fitted: Next-to-skin without the squeeze HeatGear fabric is ultra-soft & smooth for extreme comfort with very little weight UPF 30+ protects your skin from the sun's harmful rays 4-way stretch fabrication allows greater mobility in any direction Moisture Transport System wicks sweat & dries fast