Inner rack type backpack

Generally, to buy a hidden waterproof backpack, first watch the suitcase backpack's structural design must have the following basic things:
Whether the bottom of the backpack is double-layered can increase the durability of the luggage backpack. The extension bag at the top of the backpack must be able to extend upwards again, while the stretch bag must be able to seal. The tight belt on the outside of the backpack must be able to tighten the backpack's volume and prevent it from shaking. Backpack side pockets must be easily removable. Backpacks must have traction rings and ice axes to carry crampons, snow shoes, and other items. The durability of the backpack meets your needs.
The degree of waterproof treatment of the backpack. If the zipper failure can continue to use. The backpack must be waterproof. Although the backpack is waterproof, the rain still seeps through the seams, the top of the pocket or the zipper seam.
After checking the appearance, take the backpack back and look at the mirror. Note the following:
The backpack skeleton must be 2 to 4 inches above the shoulder, and the upper bag must not exceed 5 or 6 inches over the shoulder, otherwise a backpack will be selected. When carrying the belt, the center point of the belt must be in the middle of the ischium, and the end of the waist gasket should not be too close to each other and the part without the gasket can not rub the stomach. Do not choose the belt that is too tight. Adjust the shoulder strap fixing point. The curve of the shoulder strap must be close to the back of the bearer. The shoulder strap should be about 2 to 3 inches lower than the top of the shoulder, and the two hands should grasp the end of the shoulder strap. The fist must be lower than the armpit. The head cannot hit the top cover of the backpack and cannot obstruct the helmet. The chest strap must help the bearer overcome difficult terrain.