CatWatch continues to be the most effective cat deterrent we have tested and with the completion of a two-year scientific trial it is the only cat deterrent tested and recommended by the RSPB. It will detect a cat\'s movement up to 12m away in an arc of 100 degrees creating a protected area of 125m square. 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 UK made unit can run on a 9 volt high quality or Duracell battery or a 12 volt mains adaptor, which increases the effectiveness of the unit by up to 30%(Available separately). For larger areas, two CatWatch units can be run off one adaptor, using a connector kit and an extension cable. (Available separately).