Round dolly simplifies moving around empty or full trash receptacles (sold separately). Simply set your empty receptacle on the dolly and lock it into place with a quick quarter turn. Full or empty, the receptacle rolls easily where you need it on the five nonmarking 3-inch gray casters. Dolly is designed to fit round Genuine Joe trash receptacles that hold 32 or 44 gallons. Dolly is made of heavy-duty engineered resins.