A martingale collar is a type of dog collar designed to prevent dogs from slipping out while still being comfortable. It consists of two loops: a larger 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. These collars are particularly useful for sighthounds and other breeds with narrow heads, as they help keep the collar securely in place. Unlike traditional collars, martingale collars provide a gentle tightening effect, making them a safer option for training and walking.