This one has batteries located toward the bottom, and you can order them with additional batteries that stack up through the center tower.
@amangons I agree that the look is not really appealing. It would be better if it were wider all around and had a decent surface to set a laptop on. I think the idea for this thing is that you roll it up next to a table or a desk and plug it into whatever is on the desk or table. It would be cooler if it were a roaming table though with batteries built in.