Silk is by far the preferred material for sleeping bag liners. Luxuriously soft, incredibly lightweight and remarkably packable, it is one of the most weight and space effective sleeping solutions available. Silk is natural and sustainable. It is hypoallergenic and soothing to the skin. In spite of its delicate appearance, silk is robust and its smooth surface resists soil and odors well. Silk wicks moisture away from the skin and is quick and easy to wash and dry. Its natural temperature-regulating properties give silk this paradoxical ability to both cool and warm as needed.