Just got this jacket in the mail and it seems pretty awesome. Good quality, lightweight. I'm 5'9 170lbs with 42" chest and the M is good with no layers. Could put a 200 weight fleece under it and it is a little too snug for me in the arm pits. I need it for layering so i had to return it. If you have broad shoulders i doubt this would work for you very well. If you're 5'9 average build with 39-40" chest which is average this would be a great jacket to own. 5 stars cuz if i was built like most people this would be an amazing jacket to own.