New Anti Barking Device,Dog Barking Control Devices,Rechargeable Ultrasonic Dog Bark Deterrent up to 16.4 Ft Effective Control Range Safe for Human & Dogs Portable Indoor & Outdoor(Blue) Anti Barking Device: 2-in-1 ultrasonic Dog Trainer is a professional device for Dog Training and Dog Bark Control. The ultrasonic emitted by the Ahwhg bark control device can attract the attention of dogs and help prevent dogs from barking, digging, scratching, biting, climbing on furniture and other unwelcome behaviors. (For the best training results,please ensure continuous use for more than one week) Two Safe and Effective Frequency: This bark control device can emit 25KHZ fixed frequency and 30KHZ variable frequency, which humans won't receive but it works for dogs. The dog whistle to stop barking has no shock, no vibration, no noise,no touching the dog's skin, nor will it affect the dog's hearing,so harmless to dogs. Suitable for small medium large dogs.