I'm 5'9", 172 lbs, 34" waist, muscular and wear 42S jacket. For me, this shirt in a large has perfect sleeve length (32"-33"), about 17" collar diameter (is a bit loose), and fits well across my chest. Only complaint is the length; it hangs past my rear end and needs to have 4-5" trimmed off the waist to fit properly. Compared to other similar shirts I've ordered and returned, this one and an Ogeenier are closest to fitting so far.