U.L. Down: 'Ultra Light Down' is used in women's and men's jackets. The concept is to make the lightest and warmest insulation layer available. U.L. Down jackets weigh less than a t-shirt, blocks more wind and is warmer than even the heaviest fleece jackets and compress to the size of a water bottle. This outerwear can be used when warmth is critical, minimal weight is paramount, and space is at a premium.