This is one of the best travel backpacks and possibly the most versatile backpack out there.First of all, it is definitely carry-on sized. I've attached two pictures: one of it in a airport measurement container and another with a measuring tape.Here's a list of important features for travelling and hiking backpacks:Yes - carry on size (22 x 14 x 9)Yes - front loadingYes - proper hip beltYes - durabilityYes - low weight (preferably around 3 lbs)Yes - water bottle holderExtras:Yes - laptop pocketYes - organization pocketYes - air panel for back air flowYes - conversion into daypackYes - extra side pocketsNo - ability to hide the straps if checking it inPossible - lockable zippersNo - rain coverNo - pockets on hip belt (though I've never used any)This backpack meets all the main criteria. It is 2.7 lbs and 2.2 lbs without the hipbelt. It is definitely a proper hip belt meant for hiking. I haven't hiked more than a mile with it yet though while travelling and haven't gotten to take it out for a spin yet. It is both front loading and top loading. It works quite well.Now for the extras for travelling, the only features this may be missing are the strap hideaway (which don't make sense for a carry-on/gate-check), hip belt pockets(never used them), and the lockable zippers. Regarding lockable zippers, they are quite easy to convert with steel wires, oval steel sleeves, and a pair of crimpers. It takes a few minutes with the right tools.The laptop pocket works well and doubles as a hydration sleeve. While travelling and having everything packed tight, it may be more difficult to access. The two water bottle holders fit normal size water bottles and I haven't had one fall out yet. I haven't tried larger sizes yet. There is an organization pocket in the front that also has a padded 8x11 area that is perhaps meant for tablets. It has a few smaller pockets in there, nothing special or closable. The two side pockets are reasonably sized and then there is one pocket at the very top of the backpack which has a keychain extension in there. Note that only the main zippers and the organization pocket can be converted into lockable.Regarding hiking features, there are molle loops at the bottom of the bag. The hip belt is pretty fantastic and the straps are adjustable. There is excellent padding and airflow in the back, much better than the 2015 version. On the front of the pack is a stowaway pocket between the organization pocket and the main pack. It's nice to be able to roll up a jacket and hook it in there. Picture attached. The side pockets also serve as a passthrough for storage of hiking sticks and what not. There are loops on the front, too, except they are now hidden. And, of course, the bag is 2.7 lbs with the hipstrap.As a daypack, it is possible to remove the aluminum stay and the hipbelt and it becomes 2.2 lbs. Picture attached. Note that since the aluminum stay is no longer visible like the 2015 version, it is much tougher to put back in. In fact, it could take a pair of pliers to remove it in the first place.Back to how much it can carry for travel, using packing cubes:Large cube (13.75" x 12.75" x 4")- 2 jeans, 2 shorts, 1 swim trunk, laundry bagMedium cube (13.75x9.75x4) - 8 t-shirts, 1 short-sleeve collared shirt, laundry bagSmall cube (11" x 6.75" x 4") - other stuffAnother small cube could possible fit here at the top.On top of all of that, there are a lot of nice little details. The compression straps have a little elastic attached to them and can be rolled up. The front tablet pocket is padded. The chest strap can be adjusted up and down.There is still room for improvement though. The 2015 version was slightly roomier. The side pockets were bigger also. Lockable zippers, attached rain cover, ability to hide straps, and maybe some hip pockets would make this backpack close to impossible to beat.As it is, this is definitely the best backpack I've owned.