PetSafe 500' Boundary Wire Expansion Pet Fence Kit with 50 Training Flags & Connectors is suitable for any size pet up to 250 lb. This kit expands your existing In-Ground Fence up to an additional 1/3 acre, providing more freedom for your furry friend. It includes 500 feet of solid 20-Gauge copper insulated wire, two wire nuts, and 50 boundary flags to help your dog understand his new boundary.