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