underground fence - petsafe stubborn dog collar with 2 free batteries petsafe this extra receiver collar can be used to add another dog to any petsafe in-ground fence system or as a replacement collar to the stubborn dog in-ground radio fence (pig00-10777) or any petsafe or sportdog in-ground dog fence. will not work with the pig00-13619 or iuc-4100 ultrasmart or yardmax pig00-11115 systems petsafe designs the products with pets in mind and they are always looking for new ways to relate to and care for our pets better. petsafe is the world leader in bark collars, underground dog fences, wireless pet containment, pet doors, dog training collars and dog agility equipment