Bests & Worsts Reviews from Amazon

This was the second such unit purchased within a month. First unit activated at 3 feet not 30 ft. Ultrasonic tweeter totally inoperative as evidenced by my young dog, within 2 feet of the unit, not responding at all! Second unit activated at 10 feet not 30. Tweeter activates but same dog 5 feet away perked up her ears but was not "repelled"! I believed there is a design defect and should not be sold as advertised. Both units will be returned.