The Halti Link is used to attach the Halti headcollar to your dogs collar. This reduces the possibility of more anxious or boisterous dogs being able to remove the headcollar. Simple but very effective. This spare link comes in one size.DirectionsFor your Halti Headcollar and Halti Optifit Headcollar, tie a knot using the stitched loop on the Halti Link to the metal ring and clip onto your dog's collar. Full supervision from an adult must be practiced at all times.Box ContainsCoA HALTI Link Black.