The flags give your pet a good visual of where he needs to stay away from. Having enough boundary flags, to cover the fence line properly, is very important. Flags that are placed 8 to10 feet apart allow for too much open space. Placing the flags 5 to 6 feet gives a better visual no matter if your pet weighs 4 pounds or 200 pounds. There are many places where you can buy boundary flags for an underground fence system such as Hidden Boundaries.
Read more: When training a dog or cat to an underground electric fence, you should always use flags!