Ok so Background I'm 5'10 and 127-130lbs. I got a small, I've gotten a TON of shirts from supplement companies, this one feels incredibly high quality, I've used it to deadlift because the screws on the inside of my belt tear holes in my shorts frequently. 3 weeks in and no holes or stress on the fabric. Also perfect sizing, normally with lifting shirts either the sleeves are enormous or the waist taper doesn't actually taper. This is perfect for someone my size when pumped I fill the sleeves to a comfortable degree and it has enough space for my chest while tapering nicely at the waist. I look like I have 10lbs more muscle on my chest and it's comfortable and high quality. As a note I got mine for free but the next time I order pre or supps I'm likely to get a second, it's that good.