Ok, there's no way the Mountain Hardwear Women's Ghost Whisperer Down Vest is lighter than air, but weighing a mere five ounces, it is the world's lightest fully featured down vest. Stash it in your pack without it taking up much room, or throw it on while hiking, skiing, or climbing for toasty warmth, thanks to its 800 fill Q. Shield Down insulation. Knowing that down doesn't insulate worth a darn when it's soaked with moisture, the ingenious folks at Mountain Hardwear developed Q. Shield Down. This water resistant down maintains its heat trapping loft once moisture seeps in, making it a great insulator through wet, nasty weather. In addition, down's highly compressible nature makes this vest easily stashable. Simply fold it within its pocket stuff sack for effortless storage without it taking up much room in your pack.