The top closure was initially unfamiliar, but is now simply out of hand. The two plates are held together and rolled in a direction down. Then fix the right and left with the buckle.
That is also the reason why it is waterproof. :)
A deduction of points there, because the backpack has no inside pocket. This means that everything ends up on each other, no matter how small it is. Many things can quickly arise because disorder. Because there you have to take just as a small bag or as an alternative, where these things are kept separate.
The backpack is also very light and can be fixed on the front side with a buckle.