1. Before buying a backpack, you should loosen all the adjustment straps and add the weight, because if there is no weight, it is impossible to know the feeling of the backpack and whether the adjustment range is suitable.
2. After wearing the backpack, check whether the arc of the built-in aluminum bar matches the curve of the back. If not, check whether the aluminum bar can be bent; if it can be bent, the aluminum bar will naturally bend into a curve that matches the back after a period of use. Whether the backpack and the back contact part are comfortable and breathable.

3. The connection between the shoulder strap and the backpack must be 5-8 cm below the shoulder, and the gap between the shoulder strap and the backpack should be small. The chest strap can adjust the width of the shoulder strap opening and closing on the chest, so that the shoulder strap can be in a more comfortable position on the shoulder, and can prevent the backpack from shaking.
4. The adjustment range of the shoulder strap must be consistent with the length of the back, so that the center of gravity can fall in the ideal position; the hip strap must be able to be tied on the crotch. When carrying the backpack, you should be able to see the buttocks and legs from the back. Women with smaller stature should pay special attention to this. Do not only see the backpack and calves from the back when carrying the backpack. This is very wrong and dangerous.