There are no internal and external brackets, no good carrying system, and almost the same as the student's backpack. Lightweight and small. However, the simpler carrying system cannot withstand large loads and is uncomfortable to carry. Only suitable for general urban tourism, one-day excursions, or one-day suburban climbing.
The metal skeleton is outside the backpack and is now rare. This bag has an H-shaped metal frame (the most common aluminum alloy) on the outside, and can be attached to the outside of the camera box, furnace, etc., so it is very large.
However, compared with the inner frame, there is more space between the body and the backpack, so that there is better air convection between the body and the backpack, and it can be kept cool and comfortable when carried.
However, when the bag is fully loaded, the outer frame has a higher center of gravity and is more dangerous in poor road conditions. When drilling in the jungle or bamboo groves, the backpack is easily caught and stuck, and it is easy to shift the center of gravity and lose balance when climbing. So this package is more suitable for carrying large pieces of luggage on a flat road.
Move the metal skeleton to the inside of the backpack, so that the skeleton and the backpack are integrated into one, which is the type of mainstream mountaineering bag. The backpack is more comfortable to the body, making the center of gravity more stable.
This will make your activities more flexible and easier to balance than the outer frame. In particular, most brands now use an adjustable carrying system that adjusts to the size of your body and is comfortable to carry.