I got this bag to replace an older version I have carried around for nearly 3 years. My biggest complaint with the old similarly-styled bag was that it frequently fell off my shoulder, particularly in the winter when I had on multiple layers. I was overjoyed to find that the adjustable strap on this new bag is much longer than the old one, making it simple to adjust all the way out and wear it across my body, instead of having to wear it on my shoulder (my former bag did not adjust far enough to comfortably wear across me, shoulder only). I chose this particular bag as a replacement because it is made of PET- PolyEthlene Therephthalate- basically, recycled plastic. The internal pockets are the same as the classic Healthy Back Bags, but this version comes with A LOT more external pockets! My former one had 4 external pockets (one if which everything always fell out of anyway), this one has 6, all of which have zippers or Velcro, or are substantially deep enough that nothing is going to fall out unless you literally hold the bag upside down and shake it violently. I'm so glad I got a new Healthy Back Bag- and in case you're completely unfamiliar with these products, this size (which is called "small") holds a TON of stuff. I drink lots of water and am never without my 36-oz nalgene bottle, which fits in this bag, along with lots of pens, a leatherman, my wallet, a packable style reusable grocery bag, clump of car keys and pepper spray, sunglasses, paperback book, planner calendar, mini-flashlight, my other new toys called Buffs (check out [...]), small pair of headphones for when my office mates decide to Skype next to me....and other various articles that wind up in there. Yes, it is heavy enough to use as a weapon (especially with my stainless steel nalgene in there!) but really is designed to carry that much weight and stuff very comfortably, without back strain. I love these bags, they are a great investment- are well made, useful, practical, and just lovely.