Why I'm stoked right now. Being 6'3, with a slim build, it's difficult to find garments that have sufficient arm length that also fit my chest/torso/waist. Usually I have to get an L or an XL to get sleeves that are long enough for my lanky arms. But in an XL I look like a skinny guy wearing a fat man's jacket. I checked the BD sizing cart. I measured my arm length and chest circumference. I already knew my waist size. And then I did a double take. According to the sizing chart, BD says I should order a medium? What, what, what? It was a tense five days waiting for my jacket to arrive. I haven't worn a Medium ski shell since I was in middle school. But it arrived. And I tried it on. And it fits amazing! Finally, a shell that fits my slim figure but with enough arm length. My waist is 33". My arm length (from spine to wrist) is 34". I forget my chest measurement. Some people might say that this jacket runs large. It's interesting what BD did. The medium and the large have the same arm length. So, if you're 6'3" and slim, like me, the medium is "true to size". But if you're a portly 6'3", than the large would be truer for you. If you regularly wear a medium, this medium is gonna feel like it has really long sleeves.