Ultrasonic Dog Repeller: Produces a very strong ultrasonic sound, when the dog hears the echo, it will feel uncomfortable and afraid of people, people can't hear it. Dog Training Equipment: It can effectively stimulate the dog's nervous system, so that it can be guided by the owner. There are infrared lamps to help you make the dog follow you, you can train your pet's company through your personal hobbies. Portable: Comes with a lanyard, convenient to carry anywhere, such as jogging or walking, cycling, parking, etc. Easy to Carry Usage: Open the battery cover first, then insert 1 9V battery (not included), turn on the switch and it works well, they also can be used as a flashlight if needed.