This set of four heavy duty all purpose dollies designed for industrial use & is built to last. The frame is made of a heavy duty cast iron and has a round recessed base for equipment with legs. The use of these dollies can accommodate long & awkward objects that other dollies can’t. Items can also be place on top of the dolly. Each dolly has a capacituy of 630 pounds and a combination of four of these tri-wheel dollies can give you a capacity up to 2,520 lbs when the weight is distributed evenly. Made in the USA!