Great work out shirt and baseayer for other activities. You can wear it out in the sun and it keeps the sun off of you. Its thin because its designed to keep you cool in the heat. Not warm in the cold. I had to buy a smaller size than usual because the arms were too long. So it fits a little more snug than its probably designed for but overall great shirt. I am 59, 155-160lbs and I bought a small after returning the medium. It didn't fit in the shoulders either. I wear a 40 sport coat for a reference as well.