The series of electronic fences are very safe and reliable for dog training. They are inexpensive electronic pet fences. Harmless wired electronic signals are sent through transmitters to form a bordered “yard”. When your dog approaches the set edge, the receiver on the dog’s neck will start beeping to warn the dog. If your dog continues to cross the set boundary, the receiver will begin to warn the dog by vibrating Or the static stimulation will increase in intensity until the dog returns to the “safe zone” - the range you set.