Ultrasonic Pet Bark Control Dog Bark Control Stop Bug Repellent Muffler Training Tool FEATURES: Pet Friendly Bark Control: This ultrasonic bark control works by sending a steady frequency sound that only dogs can hear, preventing dogs from barking and calming them down. No irritating smell, no electric shock, anti-barking only works when the dog barks. Bark repellents are harmless to human and dog hearing and are ideal for creating a quiet sector for dog lovers and deterring unwanted behavior. Effective for dogs of all sizes: Ultrasonic bark repellent has 3 adjustable sensitivity and frequency levels (15-30 kHz for large naughty dogs); 20 kHz for educational dogs; 30 kHz for small dogs) Prevents dogs of different sizes from barking easily. Adjusting the frequency weekly can maintain the training effect. EASY TO USE: This rechargeable dog bark control with LED indicators is easy to use. When you are working on 3 different levels, the indicator light flashes blue every 6 seconds; the red light is on for 3 seconds when the sound is triggered; the red light flashes when the battery is low. OUTDOOR AND INDOOR USE: The human bark unit and portable hook with IPX4 rain protection can be easily hung on trees, walls or fence posts. But when it rains heavily, it's best to bring it back to prolong its life. The ultrasonic dog device can be placed on tables, walls and shelves with a height of more than 1.5 m, and can be adjusted more effectively for barking, digging, fighting, etc. Material: ABS packaging