While the product is well-made, it runs extremely small. I ordered the large, having consulted both the sizing chart and other reviews. Many of the latter noted that it was tight in the chest, which I figured should not be a problem, as I'm pretty flat-chested. Despite that, I can't button the shirt at all without the risk of ruining it. Fortunately, it still looks very good worn open, as a shrug, so I'm not totally out-of-luck, but size up if you can, and if you think only the Large will fit you, just be aware it probably won't.