HeatGear® is our original performance baselayer—the one you put on first and take off last. So we made it extra comfortable by wicking sweat and stretching so you can move no matter what. Our original HeatGear® fabric is super-light, breathable & dries fast Mesh underarm & back panels for strategic ventilation Material wicks sweat & dries really fast Ergonomic design keeps seams off high abrasion areas & increases durability Odor control technology minimizes odor Body: 84% polyester/16% elastane