Under Armour Sonic Heatgear Fitted L/S T-Shirt - Men's The Under Armour Sonic Fitted T-Shirt gives you superior four-way stretch fabrication performance without restriction. Anti-odor technology keeps your gear fresher, longer. Contrast colored, smooth flatlock seams allow a full range of motion without chafing. HeatGearŪ is best for weather between 75 and 100 degrees. 90% polyester/10% spandex. Imported.