CatWatch continues to be the most effective cat deterrent we have tested and following scientific trials it is the only cat deterrent tested and recommended by the RSPB. CatWatch continues to be the most effective cat deterrent we have tested and following scientific trials it is the only cat deterrent tested and recommended by the RSPB. CatWatch will detect a cat\'s movement up to 12m (40 feet) away in an arc of 100° creating a protected area of 125m². When activated the unit emits bursts of ultrasound specifically designed to deter cats and will continue to do so until the cat leaves the protected area. Birds and other animal species are not affected. The unit can run on a 9 volt battery or a 12 volt mains adaptor, which increases the effectiveness of the unit by up to 30%. Run two CatWatch units off one adaptor, using a connector kit and an extension cable.