Herm Sprenger Ultra-Plus Training Dog Prong Collar with ClicLock, 18-in neck, 3.25-mm wide Adjustable up to 18 inches Designed to help with training, especially commands like heel, sit and stay. Fastening plate provides a more secure connection. Gently pinches your dog's neck, mimicking the pinch a mother dog gives her puppies. Paw-fect for walking strong pullers and large dogs, or during obedience training. Paw-some for walking strong pullers and large dogs, or for obedience training.