http://www.paw-rescue.org/PAW/PETTIPS/DogTip_Collars.php http://www.paw-rescue.org/PAW/PETTIPS/DogTip_Collars.php Partnership for Animal Welfare: Collars and Sense http://www.paw-rescue.org/PAW/PETTIPS/DogTip_Collars.php PAW Rescue: Collars