Big Cheese Advanced Pest RepellerWelfare friendly plug in sonic rodent deterrent combines ultra sound and electromagnetic action to humanely repel rats and mice from the home Dual action combines ultra sound waves and electromagnetic action to pulse through household wiring to reach rodent nest sites within walls, ceilings and wall cavities in the home Ultra sound, electromagnetic deterrent unit protects areas in the home of up to 37 sq m safe for use around children and pets such as