Suitable Size: The size of the handheld dog trainer is 13.7 x 5.5 x 2.5 cm/ 5.39 x 2.16 x 0.98 inches; use High-quality material: The material of this handheld dog trainer is made of plastic, safe and reliable, not easy to wear and tear, durable for long-term use, repelling dogs that bark at you, but safe for dogs Ultrasonic Bark Stopper: This handheld dog repellent trainer uses ultrasonic technology; when applied, it produces ultrasonic waves; the frequency of the ultrasonic waves will stop your dog from barking; it is suitable for all breeds and sizes of dogs; the frequency is safe for pets , has no effect on human ears; but it should not be applied for too long, it may not be effective for dogs Simple operation: first open the battery cover, then put in a 9V battery (battery included), turn on the switch, it can be used to train dogs, as long as the battery is charged, it can work normally, and can be used as a flashlight when necessary Multiple Uses: This handheld dog repellent trainer uses a gentle way to warn dogs not to bark; Fighting, etc., can give you a quiet environment, prevent your dog and neighbor's dog barking from disturbing you