I'm 5ft 8in, 175lbs, 40in bust, 35in waist. The medium size fits me very well (not tight). I can't say that about the Mountain tech II, which is one size smaller. The middle one looks like a small one. I have 5 of these shirts, great shirt, dries quickly. This shirt is very stylish, I've used it on the Inca Trail, Camino de Santiago, Via Francigena and other trails around 45-50Β°F; It wicks sweat away from the skin and into the fabric, where it quickly disperses and evaporates, keeping you dryβ¦