A martingale is a type of dog collar that provides more control over the animal without the choking effect of a slip collar. Martingale dog collars are also known as greyhound, whippet or humane choke collars. ... The larger loop is slipped onto the dog's neck and a lead is then clipped to the smaller loop.
Martingale ensures that the collar never slips up. They are effective training collars and help reduce pulling and tugging. Moreover, they are loosely fitted and only become tight when the dog pulls on the leash.