What I find most useful and unique about this adaptable rolling cart is that it folds to a relatively compact size that I can easily fit into a normal car while being able to unfold and expand to carry a large number of boxes.
I like it better than the common folding dollies that have a lower load capacity and have only two wheels that only operate in an upright position. Being able to put into a long horizontal position allows the Rock N Roller carts to carry unusual loads that might not stack in a stable fashion on a typical upright dolly.
[Rock N Roller offer this same design in multiple sizes. They seem to be a favorite among touring musicians.--OH]