PetSafe YardMax Rechargeable In-Ground Fence (Upgrade to 16 Gauge Wire) Great new dog fence system from PetSafe allows you to use up to 30% more of your yard for your dog to roam Choose from standard grade wire or upgrade to professional grade wire upgrades like 16 and even 14 gauge wire Pet Safe YardMax comes with very light, waterproof, reachargeable collar, with charger that can charge two collars at once. Yard Max is expandable to unlimited number of dogs (must purchase additional PIG00-11116 collars) Yard Max expert training guide included with every order