PetSafe Stubborn Dog In-Ground Fence, PIG00-10777 Upgraded Wire (18 Gauge Wire) PetSafe Stubborn Dog Fence with Optional Wire Upgrades For large dogs, hunting dogs, stubborn or excitable dogs, or any dog that needs something extra to get their attention Highest correction level that PetSafe makes Install it yourself and use the same wire professionals use - upgrade the wire! Free supplemental training guide