Purchased this item for a trip where I didn't want to bother with checked baggage.  This backpack easily holds enough for four-five days, while being small enough to carry on, even when other people had to check their rolling carry on bags.  Two things of note.  I got the black version, and the white stripes you see in the pictures are reflective and very obvious.  Just something to keep in mind.  Also, some pictures show a zippered side-pouch, some mesh.  Mine was mesh, with nothing on the other side.  I sewed on a MOLLE pouch to help balance things a little better.

Overall, great item, would definitely purchase again (though hopefully it is high enough quality that I won't have to!).