The Herm Sprenger Prong Collar is a specialized training tool to gain control of a dog that is difficult to handle on a leash. Fit snug around the back of the ears and jawline, the collar applies pressure evenly around the neck and not just on the trachea and larynx like a normal collar. Individual links can be removed to ensure a perfect fit. The collar should not be large enough to slide over the dog’s head, you should have to open and close it. With proper training, the dog will learn that they have control over the correction by not resisting and the pinching action of the prongs simulates the dominance biting of a more senior pack member. The prongs have rounded blunt ends to prevent injury and the entire collar is constructed of chrome plated steel. Measure your dog’s neck high, right behind the jawline and ears to determine the proper size.