Anti-barking device: Ultrasonic dog trainers are great devices for dog training and barking control. Ultrasonic frequency (25KHZ) has a certain effect on dogs and can help you correct their behavior. The dog barking control device adopts high-pitched ultrasonic design, which is harmless to pets and humans. The barking prevention device can be used indoors and outdoors because the barking control device is ultrasonic, which means humans can't hear the stop barking dog device, but dogs can! The dog bark deterrent gets your dog's attention without causing pain and irritation. Safe:dog barking deterrent is an in barking control devices that corrects bad behavior and stops dogs from barking. It is effective on all types and sizes of dogs from 6 months to 8 years Ultrasonic Barking Control This controller uses the latest ultrasonic technology to silence the dog and avoid the dog from barking too loudly. It is more deterrent and waterproof than the old version. Material: ABS colour: black Package Contents: 5 x dog repeller Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.