I brought 3 ball locks to Lowes yesterday to test-fit any/all 5cf they have, and this one held three on the floor with a little room to spare. I forgot to bring my 5lb CO2 tank, but the hump wasn't terribly tall, so I'd imagine you could fit 2 5gal plus 1 2.5gal on the floor, and 1 2.5gal and...