The GoRuck packs have an internal frame sheet. It works well, for me, with fairly heavy loads for the size of the pack. I expect that with the largest pack (the GR3) if it was packed more heavily than I use it that the frame sheet wouldn’t be good enough,.
I have most of the GoRucks. The frame sheet on the GR3 is very thick and stiff compared to the others. The pack will easily support more weight than I am capable of carrying.