Perimeter In-Ground Dog Fence - 1000 Feet of 16 Gauge Upgraded eXtreme Wire 1000 Feet of eXtreme Brand 16 Gauge Wire Upgrade, for 20+ Years of Reliable Performance Without Degradation Solidly Built and Geared Toward Most Dogs, 8-120 lbs. Unlimited Dog Capacity (With Purchase of Additional Collars) Can be Expanded to Contain up to Up To 5 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 are capable of 4 unique correction level settings and 1 progressive setting that automatically increases as the dog continues towards the boundary line.