The Cat & Dog repeller incorporates a sophisticated Passive Infra Red detection system which constantly monitors a fan shaped area of a 70 degree arc up to a distance of 12 meters. The Cat & Dog repeller detects animals moving into this area and triggers a burst of continuously variable ultrasound, which sweeps a frequency range of 18,000 Hz - 24,000 Hz to repel them. The Cat & Dog repeller is powered by two 9V alkaline batteries. A 9VDC Mains adapted can be bought seperately to power the device. The unit is water resistant.