Under Armour Boys' Undeniable &frac34; Sleeve T 100% Polyester Imported UA Microthread technology in the fabric dries faster, wont cling to you, wont chafe & stretches without absorbing sweat HeatGear fabric is ultra-soft & smooth for extreme comfort with very little weight Stretch-mesh back panel delivers strategic ventilation 4-way stretch construction moves better in every direction Material wicks sweat & dries really fast