Trains & Corrects Dog BehaviourDog bark deterrent device emits an Ultrasound, LED Flash or Beep that pet will immediately notice and realize that its behavior is making you unhappy. With dog control devices, you can better train and correct dog's bad behavior. Safe & EffectiveThe 20~25KHZ ultrasound cannot be received by humans, but it works for dogs, and it is Harmless to humans and dogs. Up to 25ft range effect, the ultrasound dual heads are able to give commands faster and further. 3 Deterrent & Training Undulating ModelStable Model, Undulating Model and Irregular Model, the ultrasound works with a LED FLASH, and the dog bark deterrent device VIBRATES. It is recommended to cross-use each mode. Beep Sound TrainingPress and hold the Beep Button to deter your dog's behavior and stop it immediately. Press the Beep Button repeatedly, and replace the dog whistle, the ticking sound will train your dog's daily behavior. Adjusts the training mode according to the dog's behavior. Small & Easy to Carry & UseDog bark deterrent device has an attractive and non-slip pattern on the body and the slim design can be operated even by small hand. With a working light and vibrating design, you don't have to worry about false triggers. With a portable wrist strap, you can free your hands at any time.