The ultrasonic bark control device comes with a dog training whistle. Ultrasonic Technology: This bark deterrent uses ultrasonic sound waves at adjustable frequencies of 15kHz, 20kHz, and 30kHz to stop excessive barking. Effective Range: Covers an area up to 50 feet, making it ideal for indoor and outdoor use to control barking in homes, yards, and kennels. Easy Operation: Simple dial control allows you to switch between different frequency modes or turn the device off as needed. Compact and Portable: Lightweight and compact design with a hanging hook for convenient placement and portability. And it's IP4X waterproof. Safe for Pets: The ultrasonic sound is harmless and only audible to dogs and other pets, not humans. Silence unwanted barking with this ultrasonic bark deterrent device. It emits high-frequency sound waves that only dogs can hear, effectively stopping excessive barking without harming them. With three adjustable frequency levels (15kHz, 20kHz, and 30kHz), you can find the optimal setting for your furry friend. The compact design allows for easy placement both indoors and outdoors. Give yourself and your neighbors peace and quiet while humanely training your dog not to bark excessively. Measures 4.5 x 2.5 x 1.5 inches.