This versatile piece can either be used as a warm midlayer with a shell over the top in wet and windy conditions, or it can be used on its own when moving fast in cold, dry conditions. The Phoenix features a slim, tapered fit with an average length, however due to its stretchy nature it will accomodate a range of shapes and sizes. The stretchy fabric over the rear of the shoulders allows a full range of motion if you're climbing or mountaineering, while the articulation in the arms increases comfort even further. The stretchy STRIA Lite fabric for the side panels allows for the maximum range of motion, but still has afleecy inner sidefor warmth and breathability. I've found this is great for temperature regulation when hillwalking or climbing, and the additional benefit is that it gives you a neater shape (for less bulk, and for a nice slimming profile).