Don't let the light weight fool you - the Synthetic Down Vest is incredibly warm and extremely versatile. The vest is also PACKABLE and zips into the internal chest pocket, making it the perfect size for storing in a backpack or in your vehicle. Wear it alone as an outer layer, or under your waterproof outerwear when you need extra insulation. We used synthetic down insulation when designing this vest because it offers light weight, uniform loft throughout the garment, and it won't mat down like natural down. Average weight is just 9.2 ounces (size Large). When packed, it measures 8" W x 7" H x 4" D and can be compressed even smaller. The stuff pocket has a carabiner loop for clipping the jacket to a backpack.