Herm Sprenger Stainless Steel Extra Link for Prong Collar ( 3 pcs pack ) 1.5mm / 2.25mm / 3.2mm / 4mm : Prong Collars, Pinch Collars, Dog Training Collars, Curogan Collars, Chain Dog Collars, Fur Saver Collars, Choke Dog Collars, Herm Sprenger Collars, Dog Muzzles