The total capacity of the pockets is about 5-6L. The "single pocket" would fit a typical rain jacket and pants set, or a set of tent (or solo tent flysheet) with pegs and guy lines, while the "twin pocket" is a shallow two-tiered pocket suitable for snacks or small items like a headlamp. In either case, the capacity is not that large, so it should be treated as a secondary item.

However, even though it's simply called a "sub," it's also true that having that extra space or surplus space contributes to the "comfort" of the mountain trip itself. Things you really want to put inside your backpack but don't want to lose their shape, or things that are wet, or things you might need again soon, are somehow difficult to fit into your backpack... Such "packing worries" often arise during mountain trips. Many people have experienced firsthand that in times like these , having "space to just roughly throw in" is more convenient than its actual capacity . We believe that creating this "excess space" is the purpose and value of this pocket. And for those who "usually pack with a front pocket in mind," this pocket, although an add-on, fits seamlessly and provides natural ease of use.

However, one thing to be aware of is that the front of the backpack is also the part farthest from your body, so if you put something very heavy inside (such as water or batteries), it will be pulled downward and backward while you are walking, which can put a lot of strain on your shoulders. People who tend to put everything in their backpacks should be careful.