?Features: 1.Durable weatherproof for indoor outdoor use2.Use low-intensity ultrasonic, silent to humans, no harmful3.Use ultrasonic sound to deter unwanted barking, more effective4.Detects barks up to 50 feet with the waterproof sensitive internal microphone5.Four levels of operation including a test mode. Switch with 4 Levels of Operation: Test-used to verify the microphone and speaker are functional - 1=Low Range-up to 15 feet - 2=Medium Range-up to 30 feet - 3=High Range-up to 50 feet?How It Works?1.When the outdoor bark control is within range of a barking dog, microphone pick up the sound and unit is automatically activated.2.The outdoor anti bark control emits an ultrasonic sound.(ultrasonic sound can be heard by dogs but is silent to humans)3.Startled by the high-pitched sound, the dog should stop barking, it will associate its bark with this unpleasant noise.4.When the dog stops barking the ultrasonic sound also stops.?How To Test It? 1.Adjust the knob to "TEST" button.2.Place the item to a position which is one arm's length away from you.3.Whistle to the microphone of the item loudly,if the LED blinks Green,and you can hear beeping noise,then the item work properly.?Specification: Material: PlasticSize: (L) x (W) x (H) 7.7 x 6.3 x 4.2cm / 3.03" x 2.48" x 1.65"(appr.)?Package Includes: 1 x New Outdoor Bark Control1 x English Manual?Note: 1.Keep at arm?s length away from the human ears to avoid hearing damage. If a dog begins barking while you are setting up, mounting or hanging the Outdoor Bark Control.2.If the dog is deaf or hearing impaired, he may not react to Outdoor Bark Control.