1. The dog repellent is a convenient small device that can emit strong ultrasonic signals to effectively drive away aggressive dogs. 2. The dog repellent emits high - frequency waves (20,000 - 40,000 HZ), which are inaudible to human ears and extremely unpleasant to dogs and other wild animals. 3. It has a compact size and can be put into a trouser pocket. 4. It is an essential device for defending against aggressive animals. 5. You no longer need to run away from aggressive dogs. They will make way for you. 6. It can be used for training purposes. For example, it helps to teach dogs commands. 7. It is 100% odorless and does not emit harmful chemicals into the air. 8. The device does not interfere with the operation of televisions, radios, electronic alarm devices, smoke and fire detectors, and other electrical appliances. 9. It is powered by a 9V battery (not included). 10. It has a built - in LED to indicate the device's operation. 11. The integrated powerful LED flashlight will help illuminate the road and make you feel safer when walking home at night. 12. Specifications: - Material: Plastic. - Power supply: 9V battery (not included). - Frequency range: 20,000 Hz - 40,000 Hz. - Sound pressure: 135 dB. - Operating range: 7 meters. - Dimensions: 12.3 cm x 4 cm x 3 cm. - Color: Yellow. - Packaging: Color box.