fabric for the sleeping bag liner is soft, comfortable, skinfriendly, and breathable, built for longterm use. It is small, compact, and extremely light, making it a terrific accessory for outdoor activities or travel. Humanized design: The liner has a side entry opening with a snap closure to prevent slipping while you sleep. A bottom vent glides with an invisible zipper for easy ventilation, and you can open the bottom zipper if you feel hot. companion for sleeping bags: The liner can be placed inside a winter sleeping bag to help keep you warm; you can clean the liner instead of the sleeping bag. It provides better warmth in winter and can also be used as a summer sleeping bag, making it suitable for four seasons. Convenient and functional: The liner is easy to clean and machine washable, making it practical for camping and outdoor use. Its design and size support connecting sleeping mats for single, family, couples, and group camping.