Make sure you have plenty of these bright flags that teach your pet exactly where his boundaries are. Your pet will quickly learn to stay within the boundaries you have set for his electric pet fence when you place plenty of flags around the boundary area. For those properties that accommodate very large boundaries, extra flags might be needed to clearly mark the area for your pet. Don't let your dog become confused about where his boundaries are. Make sure you place your flags closely enough together and purchase extra when needed.