Full disclosure, I'm an Osprey guy. All my packs are Osprey. I just love the way they fit me and their top notch quality. Not to mention their almighty gaurantee! But I am so happy that Osprey finally addressed the need for an ultralight stuff pack. I am an adventurer who travels internationally a lot. I like to travel light and prefer carry on only when I can. Usually my EXOS 38, Talon 44 or Stratos 50 can be used as carry on no problem. But sometimes if my pack has to be checked, I need a smaller pack to put my valuables in for the plane. Also once I land, sometimes I want to leave my larger pack in the hotel or hostel and walk around town with a smaller pack. The Osprey Ultralight stuff pack is perfect for both these needs. It packs up to practically nothing and I can just throw it in with the rest of my gear without noticing. It really is amazing. It's also fully featured with an actual side water little pocket, top stash pocket for keys and smaller items as well as a fairly roomy main compartment. I can fit my camera, iPad, rain jacket and snacks comfortably. Love this thing. I used to carry my Talon 11 on trips for such uses, but no longer. The osprey Ultralight stuff pack goes with me on every trip now.