I bought a backpack for air travel, as it weighs next to nothing and you thus the 20 / 23kg actually can use with luggage and not only for the already 8kg bag it goes / the suitcase. The outside pockets are easy to fill and flexible to protect with belts. The separate base bag can be with a zipper from bottom separately Open / fill. The lid has an additional pocket and again straps for attaching sleeping pad, etc. Qualitatively, the backpack is really good and I think can compete well with the more expensive brands for casual backpackers. I would buy it again.
