3.6x More Effective Than Anti Bark Collar - Don’t subject your dog to the painful sting of a dog bark collar.2-in-1 ultrasonic dog bark deterrent devices is a professional device for Dog Training and Dog Bark Control. The ultrasonic emitted by the eladyne 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. Choose the most suitable mode for deterring your dog unwanted behaviors. 4 Adjustable Modes-Upgraded Technology: Compared to the first generation, the upgraded version of eladyne Ultrasonic Dog Bark Deterrent Devices has 4 modes,including 2 adjustable ultrasonic modes which can effectively prevent dogs from adapting to specific ultrasonic frequency,and a beep mode which is designed as a dog clicker and a dog whistle.We recommend using beep mode before ultrasonic mode emission that establishes a conditioned reflex to the beep sound,resulting in better training effect. Two Safe and Effective Frequency: This Ultrasonic Dog Bark Deterrent Devices 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.