I was surprised this wasn't cotton, which is my fault. It says, right there at the top of the page:-Quick-drying material, polyester and spandex,soft and comfortable to wear. Skin-friendly.And, it is. It's comfortable, and the primary purpose I had for it was the Memorial Day Murph. So it got soaked with sweat, although I'm not sure where the sweat went. It seemed to wick it away and poof, it was gone.I'd say if a shirt is sized right, which 80% aren't, I wear a medium. This in a large fit like See full review