I'm 6'0", 185 lbs, 32" waist, 42" chest. I ordered L. Material: 92% polyester/8% spandex. for me .It's very thin around the chest and shoulders but not too tight around the waist.The neck opening is a bit wide with a deep V-neck but that doesn't bother me.That's bad.Due to the synthetic fabric, this shirt attracts sunlight and makes you very hot to wear it outside.I haven't washed it yet but the fabric feels fragile and I doubt its durability.The length is a bit short because it sits just below my waist so it's ok when Bending up migrates. Finally, to reiterate, this shirt hugs the chest and shoulder area very well, so if your pecs and trapezius muscles aren't up to par, this shirt obviously will. EDIT: Me I have the black round neck Ordered an L cut and it arrived today. It's made from a cotton blend instead of polyester and spandex and has a looser fit. Cotton seems cheaper than synthetic, the sleeves have a cheap hat seam instead of a better folded seam, and it just doesn't fit or feel as good as heather black. I'm sending it back today.