Back in 1996, we invented the baselayer—and we've been perfecting it ever since. It took 37 prototypes and endless hours of testing to create the right light, tight layer that wicks sweat, dries fast, and keeps you cool. HeatGear® fabric is ultra-soft & smooth for extreme comfort with very little weight Mesh underarm & back panels for strategic ventilation Material wicks sweat & dries really fast Ergonomic design keeps seams off high abrasion areas & increases durability Hybrid raglan sleeve construction for added range of motion & comfort Odor control technology minimizes odor