This is very handy when you need more room for luggage or anything that fits into this large heavy duty plastic box, it sits on the heavy frame that slides into a 2" receiver hitch. It's lockable and bolted through the box into the bottom of the carrier. It rode the back of my 5th wheel across country, its very durable. The frame itself was over $100.00. It's a good deal, and the extra packing room is nice. Will hold 500 pounds of stuff. Call .