Humutan Handheld Dog Repellent, Dual Channel Electronic Animal Repellent, Handy Ultrasonic Dog Training Pet Bark Stopper for Outdoor Camping GardenThe Handheld Dog Repellent uses two ultrasonic transmitters, which can generate 130dB of ultrasound. It carries an ultrasonic that can range up to 50 feet (15M), and capable of sending a message to approaching dogs before they become aggressive in order to protect yourself from dangerous dogs while walking, Jogging, or bicycling. Ultrasound Emitted Trainer Device uses physical methods to stimulate dogs and has no effect on dogs health,thus being the