1. Multifunctional: In addition to being a pet training device, it can also prevent dog attacks, making it suitable for training various types of dogs, such as pets, police dogs, and shepherd dogs. It is ideal for outdoor work, travel, and night patrols. Note: May not be effective on large or aggressive dogs. 2. Ultrasonic design: Based on the principle that ultrasonic waves from the dog trainer can effectively train dogs to obey and stop unwanted behaviors like barking, digging, chewing, and more. It is harmless to both humans and pets. 3. Easy to use: First, open the battery cover and insert a 9V battery (not included). The sound is only audible to pets. Then, turn on the switch for it to function properly. If needed, it can also be used as a flashlight. Note: The effective range is 20 feet. 4. Handheld and practical: The device measures approximately 12.5 x 4.5 x 2.6 cm (L x W x H), making it portable, easy to carry, and convenient for activities like jogging, hiking, cycling, or parking.