This is a nice lightweight backpack that fits within some airlines' (including United's) requirements for carry-on "personal items": 9x10x17" max. This item is described as 5x11x17, but it's actually more like 8x11x17, and there's nothing stiff in the pack itself to prevent you from squeezing the 11" dimension (what I would call "width") down to 10" if you get a picky gate agent.Additional advantages:-- Very light weight but I expect it to be durable (I have one of their fanny packs that has held up very well). Measured weight 14.7 oz.-- Although mine shipped flat, it is easily folded into thirds or rolled up for packing empty in another bag.-- Great price.-- Great choice of colors (after receiving and testing, I iimmediately came back and ordered one in khaki/navy for my wife).-- Large enough to hold a medium-size laptop. Mine has a 14" display -- its case is 9" high, against the 11" dimension of the pack, so you could comfortably go up to, say, a 15.6" display.-- While the water-bottle pockets are not very deep (I've complained about this for another, much more expensive backpack), this one has a little loop above each side pocket (you can see one in the picture). You can pass a rubber band through this loop and put the two ends over the top of your bottle and presto -- falling-out problem is solved!Disadvantages:-- No padding for a laptop.-- No padding in the back of the pack to keep stuff (like the laptop) from poking you -- if it's a problem you'll have to devise your own solution, inside the pack (like a folded tee shirt or whatever).-- Not as many pockets/compartments as more expensive packs.-- The diameter of the carry handle at the top is too small to loop around the handle of your roll-aboard carry-on.All in all, a great value -- cheap enough to try even if you're not sure!