These are a 3 ton version and the base is a bit bigger 7.1" x 7.1" with a lowest height of 9.5"
https://www.gmdesolutions.com/item-d...type=equipment
Like Greg said, I would always back these up with the rolling chassis jack up near the middle of the car like in the pics above. Between the two the car is VERY steady on the lift as is.
These frames just aren't stiff enough to lift the whole back (or front) of the car from the middle like your average tube frame race car...