Petsafe Yardmax Rechargeable In-ground Fence - Pig00-11115 - Pro Grade System with 14 Gauge Wire Extreme Dog Fence&reg; Extreme Dog Fence 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 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