My friend bought this shirt, he usually wears a small. This shirt was slightly too large. (he's around 5' 8" and 145 pounds).
I'm usually a medium and the shirt fit me fine (6' 1" and 175 pounds).
Now that I got that out of the way, this shirt is absolutely FANTASTIC!
The cotton torso is very light and breathable, the arms are very durable and strong.
The sewn-in elbow pads are very flexible and thick.
The upper arm pocket are made very well and in a good spot to where you can grab whatever you got in there. About big enough for 3 packs of cigarets or a small box of chocolates or whatever unhealthy stuff you for some reason feel the need to carry with you into the field!
-Breathable, unlike a BDU top.
-Arms are very durable.
-Elbow pads in it are great
-Sizes run big. Unless your big like Arnold Schwarzenegger (both Arnolds, 1980's buff Terminator and 2010s fat governor) , you should get 1 size smaller than what you think you need.