Confetti Dots Nylon Collar Martingale dog collar. Martingale collars prevents neck injury that choke collars and slip collars often cause. Choke and slip collars can cause harm to a dog as they keep getting tighter when they pull resulting in trachea injury or piercing the skin. Martingale collars DO NOT do this. They fit loosely and only tighten when necessary and in a safe manner. Comes in blue and pink. Comes in medium and large. Refer to size chart for measurements.