I purchased this item prior to a week long catamaran cruise in the British Virgin Islands. I have fair skin so I really have to take care of our sunburns. I'm 5'10" and 175" and bought the large one. They fit perfectly, were very light and completely protected from sunburn. We snorkeled quite a bit so we were out in the hot sun and I didn't get hurt at all. I would recommend these shirts to anyone. I bought long-sleeved shirts, but I'll probably buy some short-sleeved shirts as well. Mark R Benton