Great fabric, really small
I have some Thrive shorts and love the fabric. I was looking forward to these shirts but they're really small. I have no upper body, being 5-10, 135 pounds, with about a 36" chest, and the Small was very constricting. I've put on lots of Smalls that were too big, but almost never one that was too small. I tried it with two different shirts, too, so it probably wasn't just a fluke. To add to my perplexity, I scanned the reviews again and didn't see anyone claiming that these were cut too small. But I found them very constricting around the shoulders and the shoulder/arm seam was up on my shoulder bone rather than falling off my shoulder like it should be.
A minor thing is that if you don't look closely at the picture, you'll be surprised to find that the second snap from the top is in a contrasting color, which might not be the look you want.