PolishTroll, this might help clarify things a little. My Sixmoons has the same construction Pika is talking about; the pad fits into a pocket that serves as part of the load carrying structure. The pocket is unzipped in the photo and the pad is the blue thing.



When I pull the pad out, it looks like this;



or 5 rectangular segments basically held together with duct tape. This allows it to accordion into a 2"+ rectangular block.



I picked up my pack with a removable "hoop" stay for extra stability if needed. I can easily carry 35 pounds comfortably with this pack and although it's only rated for 35 lbs max, I carried well over that reasonably comfortably. With this 1 lb pad, this pack worked for me right from the start. But, I looked into backpacks for a year before purchasing the thing. I knew specifically what I wanted in an additional pack.