This is decent and affordable rashguard. Relative to others I own, the fabric is very thin, so don't expect much insulation - but this makes it better for warm water. It's meant to be worn for surfing, scuba and other activities that require a super-snug fit. It's essentially a second-skin that keeps the sun from burning you or things from scratching/chafing you. I'm 6'0", 165 with an athletic build and fairly long torso, and the medium fits me perfectly. It feels less tight once you're in the water, but still very snug. In my experience, I buy the same size in rash guard as I do for t-shirts. If you want something loose, buy something else that's not meant to have a contoured fit.