The humble dog collar might seem like something that couldn't really be improved upon in any significant way, but ... what if you combined it with a leash? Well, what you'd end up with is the Supercollar. It's a polypropylene collar, with a three-foot (0.9-meter) retractable leash built into it. Perhaps not necessary in all situations, but there a few where it might come in handy.
Read the full article: Supercollar features built-in retractable leash