Under Armour Heatgear Flyweight Long Sleeve T-Shirt - Men's The long-sleeve Under Armour HeatGearŪ Flyweight Running T-Shirt was made with ultra-light, smooth fabric for extreme comfort and quick-dry performance. Mesh side and underarm panels provide perfect ventilation. Anti-odor technology prevents the growth of odor causing bacteria and the 50+ UPF protects the skin from damaging sun rays. This shirt features reflective graphics and logos for safety in low light. HeatGearŪ technology was designed for 75 to 100 degree weather. 100% polyester. Imported.