Herm Sprenger Extra Links for Dog Prong Training Collars | Chrome 3.0mm | 3-Count per Pack Pack of three extra links for the Herm Sprenger Ultra-Plus Prong Training Dog Collar. (Herm Sprenger Dog Training Collar sold separately) Safe, effective dog training tools with proper use Easily attaches to the collar links to add length and get a more custom fit Prong collar links feature safety ends for safety of dog and owner Great for walking strong pullers, large dogs, obedience training and behavior correction Made with superb craftsmanship from the highest-quality raw materials Includes a set of 3 links, size medium (3.0 mm) Also available in Fine Size (2.25 mm), Heavy Size (3.25 mm) and X-Heavy Size (3.8 mm)