100% Safety - This dog bark stopper does not use any liquid propellant or harmful sprays or chemical, which is one hundred percent harmless to your dogs or other pets or plants, and of course safe for yourself and your families, friends, etc. Effective Range- Equipped with upgrade 3 channel high-pitched ultrasonic sensors that have 20~25KHZ power frequency, this ultrasonic dog bark deterrent can effectively expel dogs within 5M. Multi-function- This product with 300 mAh battery and it can be rechargeable. It has three different sound wave modes, which can break the dog's immunity to a certain sound wave. Easy to carry- The handheld anti-bark repellent is tiny in size, and it can be in your pocket or take it on your hand (with hanging string).