Down sleeping bags have high requirements for internal and external materials. The lining material usually requires more than 200T, because if the lining material index is lower than 200T, some hairs will be worn out. Some good sleeping bags often use good nylon materials and will not have velvet. The phenomenon of wearing out, this material is light and feels soft when it comes into contact with skin;
Sleeping bag external materials: good down is mostly waterproof and breathable materials, because in some extremely cold places, whenever you wake up in the morning, the small drops of hot air in the tent will often splash on the sleeping bag, so the external materials of the sleeping bag should be It has a certain waterproofness to ensure the drying of the sleeping bag. Since the down sleeping bag is damp and not easy to dry, it will lose its warmth, so it is necessary to use a waterproof and breathable material as its outer fabric.