The Patagonia Down Sweater Vest delivers core warmth while keeping arms completely free. The sleeveless cut removes the shoulder-mobility constraint that makes a full jacket awkward under backpack straps, and the hip length tucks cleanly under outerwear without riding up when the pack hipbelt cinches down. What Our Gearhead(R) Experts Are Saying:"I reach for this vest when I need core warmth without restricting my arms on the approach. The 800-fill down packs enough heat into a hip-length cut that I can layer it under a shell without bulk at the shoulders."