SportDOG In-Ground Dog Fence - 2500 Feet of 14 Gauge Upgraded eXtreme Wire (3Dog) 2500 Feet of eXtreme Brand 14 Gauge Wire Upgrade, for 20+ Years of Reliable Performance Without Degradation Solidly Built and Geared Toward Medium to Larger Dogs, but Can Also Accommodate Dogs as Small as 5 Pounds, with the Right Add-On Collar Can be Expanded to Contain up to 100 Acres With the Purchase of More Wire Expandable Electric Fence System Can Accommodate Any Number of Dogs with the Addition of Collars Unique Correction Levels for All Dogs on the System (5 Progressive Plus Tone and Vibration)