With the Herm. Sprenger Extra Links for Dog Prong Collars, you can ensure the paw-fect fit for your pup. You can add or remove these links from your Herm. Sprenger Prong Dog Training Collar (sold separately) to help customize the fit. These links are available in different gauges to match your collar. They reflect superb craftsmanship and are made with quality raw materials. Their blunt prong design is safe and effective but won’t hurt your dog, making the collar a paw-some choice for walking strong pullers and large dogs, or for obedience training.