BARK CONTROL & DOG TRAINING This anti-bark device uses the latest ultrasonic technology, suitable for dogs of all breeds and sizes. Stop excessive and loud dog barking by emitting ultrasonic sound to silence the dog. The anti-bark device with 4 adjustable levels of ultrasonic volume: test, low, medium and high. Please rotate the button to test different frequency bands to get the best results. SAFE FOR DOGS AND HUMANS The most humane and widely used way to stop your dog or neighbors from barking. The ultrasound will not cause interference or harm to humans, because humans cannot hear these frequency bands, but dogs will be sensitive to these ultrasounds. However, some dogs may be afraid or dislike this sound and will not stop barking at first, so please allow up to 2 weeks for training. EFFECTIVE AND POWERFUL The new controller has a beautiful and well-designed shape. The ultrasonic penetration radius is 50 feet, covering both indoor and outdoor area. Designed to be easily