Nylon Imported 【Ultralight Fabric】WIND HARD Twilight is made of 10D ultra-light nylon, which effectively reduces the weight of outdoor backpacks; the outer fabric features down-proof, tear-resistant and water-repellent technologies, the inner fabric is soft and comfortable. 【800FP Down】WIND HARD filled with high-quality 800-fill-power white duck down. We select premium large down clusters that can easily trap more air to form a stable warm air layer. In cold outdoor environments, it delivers a comfortable sleep experience relying on excellent heat retention, allowing lightweight and warmth to accompany you all the way. 【Weight-Reduction Design】The bottomless design directly reduces the down filling amount and fabric usage at the bottom of the sleeping bag. At the same insulation level, it is usually 10%-25% lighter than a full-size down sleeping bag and has a smaller packed volume. For users who need long-distance hiking and backpacking camping, this design can significantly reduce backpack weight and improve travel comfort. A key advantage of Twilight is flexible compatibility with sleeping pads. They pair seamlessly with pads of any thickness, size or type—like ultra-thin egg crate pads and thick inflatable pads—solving the hassle of mismatches between the sleeping bag bottom and pad.The pad’s insulation layer acts directly between your body and the ground. When combined with the warmth from the down in the sleeping bag’s upper part, it creates an efficient upper-warmth & lower-insulation setup. 【Storage Method】Twilight is a lining structure with warm seams and no cold spots.When you take it out of the compression bag upon receipt,you need to lay it flat or hang it up to air, and gently pat or shake the areas where the down is uneven. It will quickly regain its fluffy and full state. When not in use outdoors, please store the down sleeping bag in a loose mesh storage bag. Keeping the sleeping bag fluffy can extend its life. Twilight down sleeping bag is truly remarkable. It is filled with 800-fill-power down, ensuring excellent insulation and protection from the elements. The fabric used is an ultra-light 10D nylon, which adds to its portability and durability. Whether for backpacking or camping, this sleeping bag is a reliable companion that combines lightweight design with superior functionality.