PetSafe YardMax In-Ground Dog Fence - 500 Feet of Upgraded eXtreme Wire 500 Feet of eXtreme Brand 14 Gauge Wire Upgrade, for 20+ Years of Reliable Performance Without Degradation Expandable Electric Fence System Can Accommodate Any Number of Dogs with the Addition of Collars System Allows for up to 30% More Yard Space for Your Pets to Play In, and Can Cover Up to 10 Acres System Emits Correction Signal Outward, From the Wire, with an Unlimited Boundary Zone Collar is Waterproof and Rechargeable and Works for Pets That Are 5 Pounds and Up