Ultrasonic design: Based on the theory that a dog trainer can effectively train your dog to be obedient and prevent bad behaviors such as barking, digging, and chewing. In addition, they are harmless to humans and pets, and the sound can only be heard by pets. Easy to use: Open the battery cover first, and then insert the 9V battery (not included). Only pets can hear the sound. Finally, turn on the switch and it can do its magic. If necessary, it can also be used as a flashlight. LED flashlight and battery indicator: The super bright LED flashlight function is very helpful when walking or jogging at night, and can also be used as a battery indicator. Portable and comfortable: Ultrasonic dog barking prevention measures approx. 12.5 x 4 x 2.5 cm (length x width x height), it can be easily put in a pocket. Ultrasonic dog bark prevention has a lanyard, which allows you to insert a dog bark control stop device wherever you need it, such as jogging or cycling, hiking, parking, etc. Multifunctional: In addition to being a pet trainer, it can also protect you from dog attacks. Suitable for training pets, police dogs, shepherd dogs and other dog breeds, suitable for outdoor work, travel and night security patrols. Product Description Anti-barking device, ultrasonic wave deter dog barking, dog training auxiliary three-in-one control (dual speakers). Specification: Frequency: 35-45HKZ. Sound pressure: 130db, maximum current: 130ma. Power supply: 9 V battery (not included). Usable distance: within 6 m Product Features 1. Fmu is scientifically designed to protect you and not harm your pets. 2. The 3-in-1 function can make your pet calm and stable when necessary. 3. Our bark control device is light, portable and easy to use. *Warning*: We recommend that you do not deliberately tease the dog with this device, because the dog will gradually get used to it and will not hate it after hearing a lot. If the light becomes weak, the battery should be replaced in time. If you use alkaline batteries, it lasts longer. The battery is not included in the package. Dog repellents can be effective for most dogs, but sometimes they are not effective for large dogs. Includes: 1 x dog barking control device.