How It Works When You Flick The Switch To On Position, The Product Starts To Work, The Indicator Light Will Flash Blue Every 5 Seconds Interval During The Standby Period, When The Switch Is Flicked To Off, The Product Is Off. The Ultrasonic Sound Have 3 Frequencies. In General, The Level 1 Frequency Works For Small Dogs, The Level 2 Workds For Medium Dogs, The Level 3 Works For Large Dogs.

But It's Better To Try Different Frequency To Get A Most Effective Frenquecy For Dogs. Package Include: 1X Anti Bark Device 1X Usb Cable 1X User Manual