I don't care how cold you are, put this thing on and you'll be warm in seconds. This jacket is a key item to have for winter pursuits. Throw it on when you stop to suck down some water, put on your crampons, grab a snack, and then throw it back in your bag and pull it out again at the summit. Windstopper rocks, and the jacket works as a "drying system" for your sweaty layers. Synthetic primaloft enables wet weather use. I'm 6', 195, and a large is perfect in the arms, a little long down the back, and enough room for layers underneath. Drawcord is key. Overall, great jacket if you wanna stay warm.