Innotek Boundary Kit for In-Ground Pet Fencing System, BD-25 Extra boundary kit for expanding an in-ground pet fencing system Includes 500 feet of 20-gauge boundary wire and waterproof wire splices Also comes with training flags to help dogs learn the boundaries Perfect for homeowners who need additional wire for larger yards Works with IUC-4100, IUC 4200, SD-2000, SD-2100, SD-2200, and more