I'm 5'6" and weigh about 155lbs and the small Karbon fits the same as my current Columbia (S) uniform jacket does. I blindly ordered the small because I rarely go to Detoilet and thankfully it worked out.

On that note, would it really have been that much of a bother to send the samples around to each base instead of leaving us to guess on sizing? Just a couple weeks in each of our to-die-for domiciles would have given most everyone the opportunity to decide if they want the jacket and what size fits best but I guess that was too much to hope for.