Awesome shirt -- my new go-to long sleeve shirt. I'm an athletically-built 6'0" /170 lbs. (broader shoulders, narrower waist), and this shirt in a medium fits perfectly. It has plenty of room through the chest and shoulders yet is snug around the midsection for a nicer, slimming look. Also, the length is perfect for wearing untucked. It falls about halfway down the zipper on my pants. The cotton is definitely a heavy-weight cotton, and it feels very nice. The only thing I dislike is the contrasting fabric under the section of the shirt wear it buttons. On the black shirt, there is gray fabric that is visible unless you button all three buttons. Same with the navy blue shirt. It looks okay, but I'd prefer if it was just monochromatic. Overall, this is a fantastic shirt. Highly recommended.