Good quality especially for the price but not very light or breathable even in moderate heat. Maybe a good winter shirt. Regarding the sizes - I followed the size chart (I have an athletic build) and therefore ordered XL and swim in it. I should have tried L. I think I would have liked it a lot better if it was true to size, but I basically ordered it because I needed it to be comfortable and breathable. The fact that he's breathing badly makes me very uncomfortable.