I did a lot of research for this one because I was in the army and I have had a lions share of tactical bags which are produced to survive harsh treatment. They all seem to lack comfort. So I wanted a bag like this but didnt know where to begin. Their sizing chart was spot on and when I put some weight in it and strapped it on, I felt like I could go on a run in it. The weight was distributed perfectly and the anti-gravity feature doesnt work against me when I bounce, which is what I was worried about, but it actually softens the impact of each step without the dragging feeling of "too much shock absorption" like you get when riding a mountain bike up a paved hill. This thing is magnificent. The only thing I worry about is the lifespan on the mesh on the back but with ospreys warranty, it eased my mind to know that this is a forever bag. Osprey just got themselves a lifelong customer. Unfortunately, I like to collect things so I know I'm going to have quite the selection to choose from and my storage space and wallet are going to be mad at me. I will be buying many more Osprey products in the near future.The only negative is that it did not come with a rain cover and they are sold separately. But that's okay because I will gladly pay it because I know my bag is covered by their incredible warranty and that's worth buying a rain cover.Great pack, excellent pack, would be perfect except...No integrated rain cover? I have $75 Osprey packs that come with a rain cover but this top of the line model doesn't... Why Osprey why. Charge me another $20 but put one in there, there isn't even a pouch for me to buy one and keep it in there. So now I have to spend $40 on another rain cover (whatever, get your money), but there isnt any designated place to put it.... So I'm just shoving it in a pocket somewhere. Seems like a really dumb oversight to the point it is intentional, but for the life of me I can't find any reasons that would motivate Osprey to do this...Anyway, really it is a small thing but this pack is SO CLOSE to perfection that that one thing just seems so dumb when so many of their other products have it.Can't beat the AG fit and comfort. I can carry loads more comfortably, and for longer distances with this pack compared to some very popular UL packs. Osprey is like no other pack, with it's anti-gravity suspension and ventilation. Some hikes I have to carry up to 7 liters of water, (almost 15 lbs) along with my other gear. After 8 or 9 hours, I'm still going, without regard to my pack load. Try THAT with a dynema pack! Life's too short to be in pain on trail...whether it's a 20 lbs or a 40 lbs, this pack will suspend it properly and allow your legs to do the lifting while your shoulders do little more than stabilize the load.PROs: -Suspension and ventilation are unbeatable.Great features and quality constructionFull life-time warrantycompletely adjustable for a custom fitCONS-Hip belt pocket zippers can be a pain to close.Will not stand up on it's own when loaded...you'll have to lean it against somethingStraps dangle everywhere...no way to secure the excess webbing.Make sure and get your torso measured. Most people make the mistake of buying a large when they need a medium, and so on. Properly pack your load, adjust the pack and hit the trail. This is a great pack.Osprey makes the best packs on the planet. They literally think of EVERYTHING. However, I ended up sending this pack back because I needed more space for a bear canister. I think if you're looking to pack for a weekend trip, then this pack is certainly a decent purchase to make! If I had one complaint, it would be the weight of the pack. However, all the comforts and bells & whistles are there. And that certainly makes for a delightful experience while you're out hiking. I love the anti gravity system. It certainly feels like less weight. I recommend this pack to everyone who is going on a weekend trip. ENJOY!!They are good, not amazing like everyone makes them out to be. Osprey has an odd cult-like following, so be careful whom you talk to when buying one. They are not as comfortable as one would think. On a long hike of more than 2 days, I felt like I was fighting against my bag as it would rub in odd places and requires small adjustments.This was my 1st backpacking backpack. I gotta say I love it, it almost feels like there’s nothing on my back despite having 35 lbs of gear in it. I was able to hike 4 miles under 1 1/2 and it was great. It fits all my gear but it could’ve been a little bit bigger but it works. It was a little painful on the way back from my trip but that was due to me not putting the straps right. Overall a 5 star bag and am looking forward to putting several backpacking trips with it!!! I’ll probably write another review in a few months after I put more use on it to see how the wear and tear is on it.I used this backback for 3 days in Nepal, and recently in Eagle rock loop trail (27 miles backpacking). The anti-gravity works great. I didn't feel the hanging load in my shoulders. The shoulder straps are very soft, and doesn't add extra pressure. Doesn't come with the Hydration pack, but I bought separately and fitted in the bag, which was a great decision.The overall quality of the bag is great and definitely recommend to all backpackers.Only complain I have (including my fellow backpackers who mentioned the same issue) is that the main compartment is reachable only from the top. It makes it hard to reach for the stuffs at the bottom of the bag. You will need take out everything and repack.One last thing: the US purchased bags DON'T come with the rain cover, but if you buy from (like my friend did) Europe you get the rain cover (extra $25).Just returned from a 3 day hike and this pack was incredible! Never felt any sweat on my back thanks to the Anti Gravity technology and the load distribution was very comfortable!How many Osprey packs would you need to become a fan club ? Since Berghaus stopped their Freeflow 50 litre I bought into Osprey. Have Daylite, the plus, the Holdall 30 litre; Sojourn 80, Farpoint 80, Farpoing 65 and 36 wheels and bought the Farpoint treckking 55 the week before I bought this Atmos 50. So why am I returning this Atmos ?It is only because Osprey, Lowepro and their ilk won't produce a 100 litre pack or greater that I had to resort to needing two packs for work assignments plus one cabin luggage to hold office equipment. For the purpose of walking for pleasure I really wanted a 50 litre pack, big enough for one or two day walks, plus full-frame DSLR with 28-300mm zoom lens inside. Already have the Exos 38 for walks in the summer. Really needed a 50 litre for winter. Tried the Stratos 50 but its ventilation holes on the back system were basically blocked (for 75% of them). The Rook 50 does not have a front pocket.Atmos 50 Features I like :-Ventilated harness. In my opinion this ranks second after the Exos for ventilation but ranks top for load stability and comfort. Osprey calls it Anti-Gravity and I have to agree they have the ergonomics of this part of the pack completely right. Full marks here.Top and bottom sections with their own access.Dump pockets both sides for hot water flasks..Twin ice axe loops.Top pocket.Another top pocket which Osprey stows th rain cover (but I remove the cover to stow elsewhere.Front section for wet cagoule or wet rope.Features I don't like or missing :-No loops for optional harness for safety helmet in outside the front sectionTwo front pockets removed as copared to Atmos 65. (On the 65 there are pockets either side behind the front elastic net section.No anchor loops on the lid (for purpose of securing crampons).Don't like the removable top lid because firstly, the extra straps flap in the winds and the extra expense in manufacturing the sack. I would rather the expense go into replacing the missing two pockets mentioned above. In fact there are so many straps the excess of which are uncontrolled after you compress them all that they become a problem. On one windy walk one of the straps hit my eye. So after the incident, had to fashion sticky electricians tape or other forms of holding down the excess straps to prevent them flapping in the wind.Osprey should look at Deuter or other manufacturers. Please put in anchor points for a safety helmet harness. I bought a Deuter harness option to fit the Farpoint 36 and 65 Wheels so Osprey can do it when they want to (just not on the Atmos.) You would have thought an Atmos user would far more likely to be using a helmet than a Farpoint user. My full face screened construction hard hat is £120 so would want to swing and bash about against hard surfaces hence the hardess for the Farpoints when on assignments.OK, not great deal, I can puit with those disadvantages..... but the following is the deal breaker. When worn normally, the hip pockets are in my way. They do nothing except chaff my lower arms, yes, even when empty. They bulge out to the side too much. This is a bad design. If I wanted, I would just buy a molle pouch to fit at the front; at the buckle, any such pouches would be out of the way of the arms. Generally I like the sack and even thought to cut off the hip pockets but they are integral to the fabric other features are attached to, as well as even after removal the padding would still be too thick. Very disappointed.Since noticing this bad design feature, I loaded and tried on the Farpoint 55 Trekking. This pack is ok because the ventilate back system is different to AntiGravity and that the hip padding is less. If the pockets are kept empty they would not chaf at every arm swing.This is without a doubt the most expensive backpack I have ever bought. 3x the price of my previous 2 bags. But a £50 Berghaus & the same price for a karrimor added together weren’t much cheaper.I wasn’t expecting the Atmos to be 3x better than the others, I’d have been happy with 50% better. But from the first time I put it on I could tell the osprey was good. I emptied my previous bag and added extra weight. Then I walked the dog for 6.5 miles! No back sweats no aching shoulders just like I was wearing a ring day sack actually better! In fact I did it again the next day & yet again hardly noticed the backpack. The waist belt grips my hips and rests most of the weight there. In fact at times I felt my shoulders moving inside the shoulder straps but the bag wasn’t flopping around behind me.I wish I’d bought it years ago!In summary I’m thrilled with it & plan to put many more miles in with the bag on my back. It’s worth the extra money.I bought this bag over a month ago to travel around South Africa, needles to say with the current virus situation my trip was cut short. However for the four days I travelled with this bag I absolutely loved it, very comfortable, so light you barely no its there and the capacity was more than enough needed for what would had been a 3 week tripSits beautifully when partially or fully full. Very accessible storage throughout and, well, it's just high quality from start to finish.I do suggest the buyer considers the next size Osprey down if they're only going this big "to be sure". It can carry a LOT of gear. It's almost embarrassingly empty on many treks. However, it is also excellent in every way and as I said sits nicely even partially filledThe bag is everything i hoped it would be. Easy to pack, simple to adjust and comfortable to wear for a 10 hour hike ?. The removable lid is an added bonus. Good build quality although the marketing people should consider whether " anti gravity" is perhaps a claim to far. Highly recommend