The Patagonia Better Sweater Fleece Vest delivers core warmth while keeping the arms completely free, the configuration that makes sense when a full jacket would restrict a pack's shoulder straps or overheat on a sustained climb. The midweight recycled fleece holds heat through a cool morning without turning into a liability once the trail kicks up, and the slim fit layers cleanly under a shell without adding bulk at the shoulders. What Our Gearhead(R) Experts Are Saying:"I wear this under a shell on shoulder-season hikes because the slim cut doesn't bunch under the arms the way a jacket does, and the vest length hits right at the hip so it stays tucked when I'm moving."