When installing invisible dog fences smart owners use boundary flags to help their part learn the limits of where they can roam.
PetSafe Boundary Flags are ideal for this and can be used with brand of underground pet fence. And after a month you can remove the flags because your dog will have learned his or her boudaries.
These flags are plastic and twelve inches tall. Each bundle contains 50 flags which is enough to mark 500 feet of fencing. These are also great aides if you have landscapers or other workers digging in your yard.