Under Armour Heatgear Sonic Compression SLVLS T-Shirt - Men's The Under Armour Sonic T-Shirt is the evolution of compression performance, giving you superior four-way stretch performance without restriction. Anti-odor technology keeps your gear fresher, longer. Smooth flatlock seams allow a full range of motion without chafing. Updated jacquard neck and lockertag. HeatGearŪ is best for weather between 75 and 100 degrees. 84% polyester/16% spandex. Imported.