Anti-bark device with a range of up to 50 feetThe ultrasonic penetration range is 50 feet, covering both indoor and outdoor areas. Compared to traditional dog trainers, it completely frees your hands. Safety Bark StopperUltrasonic frequencies are harmless to pets and completely inaudible to human ears. If the dog is hard of hearing or aggressive, the device may not work as expected. Auto ControlThe sensitive microphone can automatically detect dog barking and will automatically emit high-pitched sounds that only dogs can hear. 4 Modes Ultrasonic Dog Barking ControlThe anti-barking device adopts ultrasonic technology, which not only automatically detects barking from a distance of 50 feet via the internal microphone, but also emits sounds treble that dogs hear. Suitable for most dogs - Suitable for most breeds and sizes of dogs, except those with hearing problems or under 6 months old . Some dogs may be afraid or dislike the sound of the ultrasound and may not stop barking at first, so training can take up to 2 weeks.