This pack of an additional 50 Boundary Flags are useful for reinforcing training or expanding containment area. Place flags approximately 10 feet apart to remind your pet of his off-limits area. Between days 15 and 30, you will be monitoring your pet's progress. After you are satisfied your pet's training is complete, remove every other Boundary Flag every 4 days until all flags are removed. In about a month, your lawn will be free of training flags and your pet will know his limits.