Dog Anti-Barking Device Bark Control Training Anti-Bark USB Rechargeable Ultrasonic 3-Level Sensitivity Adjustment Suitable for All Dogs Night Barking Prevention Safe and Harmless Sleep Disturbance Prevention Black Power on, blue light flashing confirmed. Only the main unit and connection cable are included. Please prepare a USB power source separately, such as a smartphone charger. ● Product Description 【Safe and Harmless for Humans and Animals】Dogs' hearing frequency is 15Hz~50kHz, while humans' is 20Hz~20kHz. Kaiercat's anti-barking device uses 25kHz, so dogs can hear the sound emitted from the device, and adults with good hearing can also hear it, but it does not have any adverse effects on humans. Unlike electric shock or vibration devices, this device trains gently, so it won't strain your relationship with your dog. It can be used on large, medium, and small dogs. 【Ultrasonic Dog Anti-Barking Device】The emission angle is 110°, and the maximum effective distance is 10M. If used within 10M, barking will stop, no matter how much your dog barks. The LED light lets you know the battery level at a glance. Recommended for those who can't sleep because they are always bothered by their dog's barking or are causing a nuisance to their neighbors with the barking. This dog anti-barking and training device can improve sleep disorders and neighborhood disturbances in a short period. 【Sleep Disturbance and Night Barking Prevention】Recommended for those who can't sleep because they are always bothered by their dog's barking or are causing a nuisance to their neighbors with the barking. This dog training device can improve barking in a short period, improving sleep disorders and neighborhood disturbances. ※ According to reviews, effectiveness seems to vary depending on the individual dog. Therefore, we cannot guarantee the effect, so please consider purchasing it with a light heart, as if you were trying it out.