A martingale collar is a type of dog collar designed to prevent dogs from slipping out while still being comfortable. It consists of a main loop that goes around the dog's neck and a smaller loop that tightens when the dog pulls. This design allows for better control without choking the dog. Martingale collars are especially useful for breeds with narrow heads, like Greyhounds or Whippets, as they can easily escape traditional collars. They are often made from durable materials and come in various sizes and colors, making them both functional and stylish for pet owners.