Pet-Friendly Anti-Bark DeviceThis ultrasonic bark control device works by sending out a stable frequency sound that only dogs can hear, which helps dogs avoid annoying voice that causes barking. The anti-bark device is harmless to dogs' hearing, perfect for creating a quiet room for dog lovers, stopping unwanted behaviors such as barking, digging, fighting, etc. Effective on All Size DogsThe ultrasonic dog bark deterrent with 3 levels adjustable sensitivity and frequency (15-30KHz for big vicious dogs; 20KHz for docile dogs; 30Khz for small dogs) easily deal with different barking dogs. Adjusting frequency for each week can keep the training effect. The wide control range of 33ft (10m) is suitable for stopping the neighbor's dog from barking at you and your family. Easy to UseThis rechargeable dog bark control device with indicator light can be used without any effort. The light will flash blue when working; Red light when the sonic anti bark device is triggered by barking; the red light will flash in low power. The 3.7V 1500mAh USB charging battery can be used for 30 days, saving you the hassle and cost of batteries. Outdoor and Indoor UseThe humane anti bark devices with IP4 rainproof function and portable hook are suitable for outdoor use, easy to hang on trees, walls or fence posts. But if it rains a lot, it is better to take it back to help protect the equipment and extend its service life. Small ultrasonic dog training devices can be set more than 1.5m indoors, which can make them more effective.