Pestfree is a multi frequency ultrasonic deterrent designed to keep all unwanted pests out of your garden from cats and dogs to foxes and rabbitsinaudible to humans and harmless to all species it operates day and night in all weather conditions to protect garden birds your fish pond flower beds and lawnsthe 20 45khz ultrasonic output is activated by a sensitive infrared sensor when it detects any motion up to 10 metres away