I don't know. If you look at the tear downs available, the computer generated videos, and just the shape, you see what appears to be Lithium Polymer in the Jumpstarter, the Slim 5000, the Powercore II, and my guess in the Fusion also. Polymer can be made into any shape and as the polymer comes with less protection it needs added protection, the tear-down videos stop at that added protection so you cannot see the underlying make/model. The 18650B like in the 10000, 26800, 20000, etc the make/model is on the outside of the protection so its clear.
If I read the pros/cons of polymer, the need to add protection is what is preventing from safely knowing make/model, is a cause of why the Wattage output trend seems to be higher and why the density seems a little worse.
But I don't know.