The term "Dollies" refers to an axle system that can usually be broke down and stowed on the tow truck. It serves as an extra set of wheels for several towing applications. The purpose of the axle system is to provide a way to tow a vehicle that can't be rolled, whether it be due to a flat tire, AWD/4WD axles that would cause damage if dragged. There are various manufacturers that produce these tools but the principle is pretty much the same. In certain situations only a tow truck with a wheel lift and a set of dollies can be used to move a vehicle. A parking garage is a prime example due to height restrictions and the inability to get a flat bed in the structure. An AWD in a parking garage would have to be towed using the wheel lift and dollies method.
