Martingale collars are also known as Greyhound Collars or Humane Choke Collars. The Martingale Dog Collar was designed for Sighthounds (ie, Greyhounds, Whippets, Italian Greyhounds, Borzoi, Saluki, etc) because their necks are larger than their head and they can slip out of traditional side release dog collars; these collars have gained popularity as training dog collars with other breeds in the recent past because trainers prefer the humane choke aspects.
A martingale with a buckle dog collar offers the easy on/off option of a standard dog collar with the increased functionality of the martingale loop. This option is great for very large dogs with large heads because you can take the collar on and off without readjusting it each time to fit over the head..