Simple: ultralight core warmth. This vest's minimalist design practically floats, its 800-fill-power down traps heat in alpine conditions, and it's so compact it stuffs into a stretch-mesh internal pocket (with a carabiner clip-in loop). The innovative 100% recycled polyester shell with a Deluge DWR (durable water repellent) finish provides wind and water protection as well as a high tear-strength; quilting stabilizes the down. With zippered handwarmer pockets and a drawcord hem.