The Chain-Up for a single ball mount is designed to work with a standard "stinger" or ball mount having just one hitch ball that is not adjustable. Fits either a 2" or 2-5/16" hitch ball. The Chain-Up holds your trailer's safety chains up off the ground and keeps them from dragging while you are towing. The Chain-Up stays attached to your safety chains, and slips easily over the hitch ball during the trailer hook-up process. There is no faster or easier way to keep your safety chains from dragging!