A unique feature about a retractable leash is the ability to control how little or how much lead the dog is given. The nylon lead is rolled up and housed within a plastic casing that you hold in your hand. A spring-type function allows the lead to automatically lengthen or shorten (retract) as the dog travels. You hold the housing of the lead in your hand and use the lead to "reel your dog in" if necessary. A one-button braking system stops the dog from traveling any farther. It also serves as a locking mechanism should you want to keep your dog at a consistent distance.