The  Dog Repeller/Trainer can be used to deter unwanted dog or as a training device to back up your commands. The dog Repeller will produce a discomforting but not harmful high frequency sound, Audible to dogs and cats but not humans. When a dog hears the high frequency sound it will become uncomfortable and should move away or not approach any further. You can use this model to train dogs as it can stimulate the nervous system to help it follow the commands you provide. The Dog Repeller/Trainer comes with 2 settings, 1 for training your pet, and 2 for deterring aggressive dogs. This model uses No Shock Technology which is completely safe to animals and humans. This humane training technique uses a confirmed technique that teaches dogs to associate their barking with the irritating frequencies. Unlike shock collars that are painful and can be used only on one dog, the Dog Repeller/Trainer can be used virtually anywhere without you having to ask permission from your neighbors. The Dog Repeller/Trainer trains dogs to stop boredom and attention-getting barking but is designed to have no effect on instinctual or protective barking! It is also effective at deterring other destructive behaviors like chewing on furniture and jumping on guests. You control the handheld remote and you can incorporate it as a tool into your training routine. It works remotely up to 50 feet away. Dog Repeller/Trainer is often the best bark control solution for many dogs. However, it will not work for all dogs because of factors like age, hearing ability, and temperament. Safety Technology Dog Repeller/Training Specifications Material: ABS Size: Dimensions: 5 1/2" x 2 1/4" x 1 1/8" Frequency:35 to 45HKZ Power: Uses one 9V Alkaline battery(included) Our dog repeller also has the function of lighting.The light can let dogs know the source and location of sound, thus know that you are driving it away.The harsh sound will keep dogs away from the sound-producing device,thereby protecting you from attack of vicious dog when you are outdoors at night.If in a safe environment,the dog repeller can also be used as an ordinary flashlight.