This is hands down the best travel bag I have ever owned.  I purchased it to use on an excursion to some Latin American ruins.  I did not have any issues getting it through safety checkpoints.  The bag was way more spacious than I thought it would be but it was not bulky.  I was able to fit two 16 oz water bottles in the side pouches.  I also carried a small first aide kit, passport case, cell phone, water proof cases for my phone and my husband's, two ponchos, sun screen, and bug spray.  I was even able to fit the two snack packs we were given.  I carried it for over eight hours up hills and over rough terrain.  It did not rub my neck or leave my shoulders sore.  I highly recommend this product it was worth every penny.