The STV Ultrasonic cat repeller / deterrent has been designed to keep cats away from your garden and therefore prevents fouling. When the cat deterent detects movement, it emits an high pitch ultrasonic sound that onlt cats can hear and so they want to move away - very quickly. The ultrasonic cat repeller / deterrent doesn't harm cats at all, it simply produces a noise a cat wants to get away from. Humans can't hear it and it doesn't affect birds.
This STV ultrasonic cat deterrent has a 30ft range. Without the optional mains power adaptor the PIR sensor extends the battery life, only actuating the it detects movement. The cat deterrent has a test button to show that it is working correctly. It has an approximate 10 Mtr range over 98 degree arc, giving a total of 120sq mtr coverage.