Although this is a Team Fit jacket by Volcom, you don't really need to go down a size unless you like your jackets a bit fitted. It is baggier but not huge. I'm 5'10" 140 pounds and wear the size Large. It is a shell but completely waterproof/windproof. A base layer and fleece are good for most days. The length is pretty good, even for someone my height and the arms are long which is super hard to find. There's nothing more annoying then short sleeves on your jacket and you don't realize it until you bend down to do up your bindings the first day you wear it!