Because knapsack is used in special environment, it requires higher requirements for knapsack materials and technology. The positions of all knuckles are sewn three times by sewing stitches, so that the force position is strong and durable. Knuckle buckle and other components can be used to prevent freezing, prevent smashing and deformation at 120 degrees Celsius. The backpack mainly consists of 420D Oxford nylon, 1000D nylon, 600D or 1000Dpolyester (polyester), or 1000D CORDURA. 1000D material has high density and is very wearable. It is suitable for use in the field. CORDURA is a famous high-end wear-resistant nylon roving fabric developed by DuPont Co. The wear resistance of the material is much higher than that of nylon or polyester, and it is light in weight. More than 90% of the famous brand backpacks in the world use this long known nylon material. These materials can withstand the pressure of 0.5m~2m and keep the objects in the bag dry. Some materials also have anti tear function. Once punctured, the tear will not tear apart and expand.